diff --git a/changelog.d/uk-pension-wealth-split-750.added.md b/changelog.d/uk-pension-wealth-split-750.added.md
new file mode 100644
index 0000000000..44c6268923
--- /dev/null
+++ b/changelog.d/uk-pension-wealth-split-750.added.md
@@ -0,0 +1 @@
+UK WAS wealth stage emits `private_pension_wealth` (WAS private pension wealth less the current-employment defined-benefit component) as its own household output and keeps `corporate_wealth` to the share-like holdings, so the means-tested capital tests stop counting pension rights; spec, support bounds, export allow-list, coverage manifest and gate-battery digests move in lockstep (#750, uk-data#452).
diff --git a/experiments/452-uk-pension-wealth-split-coupling-receipt.json b/experiments/452-uk-pension-wealth-split-coupling-receipt.json
new file mode 100644
index 0000000000..5ef19ce3be
--- /dev/null
+++ b/experiments/452-uk-pension-wealth-split-coupling-receipt.json
@@ -0,0 +1,243 @@
+{
+ "n_estimators": 30,
+ "truth": {
+  "P(owned_land_pos)": 0.0076383512194625365,
+  "P(owned_land_pos&property_wealth_pos)": 0.0076383512194625365,
+  "ratio_vs_indep(owned_land_pos,property_wealth_pos)": 1.558018820525906,
+  "P(property_wealth_pos|owned_land_pos)": 1.0,
+  "P(property_wealth_pos|not owned_land_pos)": 0.6390839669376266,
+  "P(owned_land_pos&pension_pos)": 0.007427542905194072,
+  "ratio_vs_indep(owned_land_pos,pension_pos)": 1.3157807591526687,
+  "P(pension_pos|owned_land_pos)": 0.9724013326683218,
+  "P(pension_pos|not owned_land_pos)": 0.7372336138234814,
+  "P(owned_land_pos&shares_excl_pos)": 0.003678065948690654,
+  "ratio_vs_indep(owned_land_pos,shares_excl_pos)": 2.7087590308557132,
+  "P(shares_excl_pos|owned_land_pos)": 0.4815261622585426,
+  "P(shares_excl_pos|not owned_land_pos)": 0.17542825051479743,
+  "P(owned_land_pos&isa_pos)": 0.0015102923671691392,
+  "ratio_vs_indep(owned_land_pos,isa_pos)": 1.5441250279671401,
+  "P(isa_pos|owned_land_pos)": 0.19772491782269852,
+  "P(isa_pos|not owned_land_pos)": 0.12751351150960955,
+  "P(property_wealth_pos)": 0.6418407703588922,
+  "P(property_wealth_pos&pension_pos)": 0.5384180116374168,
+  "ratio_vs_indep(property_wealth_pos,pension_pos)": 1.1350899158187926,
+  "P(pension_pos|property_wealth_pos)": 0.8388653954412315,
+  "P(pension_pos|not property_wealth_pos)": 0.5601192967136539,
+  "P(property_wealth_pos&shares_excl_pos)": 0.15801676395202507,
+  "ratio_vs_indep(property_wealth_pos,shares_excl_pos)": 1.3849252939692862,
+  "P(shares_excl_pos|property_wealth_pos)": 0.24619309219585458,
+  "P(shares_excl_pos|not property_wealth_pos)": 0.055141870670218765,
+  "P(property_wealth_pos&isa_pos)": 0.11703642780332342,
+  "ratio_vs_indep(property_wealth_pos,isa_pos)": 1.4240158258447393,
+  "P(isa_pos|property_wealth_pos)": 0.1823449572046993,
+  "P(isa_pos|not property_wealth_pos)": 0.030749963077466483,
+  "P(pension_pos)": 0.7390299074554981,
+  "P(pension_pos&shares_excl_pos)": 0.16338613792697204,
+  "ratio_vs_indep(pension_pos,shares_excl_pos)": 1.2436657586410924,
+  "P(shares_excl_pos|pension_pos)": 0.22108190247606535,
+  "P(shares_excl_pos|not pension_pos)": 0.05510285031153905,
+  "P(pension_pos&isa_pos)": 0.11449208905849834,
+  "ratio_vs_indep(pension_pos,isa_pos)": 1.2098583447414697,
+  "P(isa_pos|pension_pos)": 0.1549221322486095,
+  "P(isa_pos|not pension_pos)": 0.051951247363071155,
+  "P(shares_excl_pos)": 0.17776633387224022,
+  "P(shares_excl_pos&isa_pos)": 0.056780288630039935,
+  "ratio_vs_indep(shares_excl_pos,isa_pos)": 2.4944174642082237,
+  "P(isa_pos|shares_excl_pos)": 0.3194096845741761,
+  "P(isa_pos|not shares_excl_pos)": 0.08667794228888633,
+  "P(isa_pos)": 0.12804981089064132
+ },
+ "D1_pension_first:same_seed_per_segment(stage as-is)": {
+  "P(owned_land_pos)": 0.00196559740097869,
+  "P(owned_land_pos&property_wealth_pos)": 0.00196559740097869,
+  "ratio_vs_indep(owned_land_pos,property_wealth_pos)": 1.5176233931560639,
+  "P(property_wealth_pos|owned_land_pos)": 1.0,
+  "P(property_wealth_pos|not owned_land_pos)": 0.658253267242873,
+  "P(owned_land_pos&pension_pos)": 0.00196559740097869,
+  "ratio_vs_indep(owned_land_pos,pension_pos)": 1.3491400871721204,
+  "P(pension_pos|owned_land_pos)": 1.0,
+  "P(pension_pos|not owned_land_pos)": 0.7407031998150472,
+  "P(owned_land_pos&shares_excl_pos)": 0.000297902582448321,
+  "ratio_vs_indep(owned_land_pos,shares_excl_pos)": 0.8991488025158029,
+  "P(shares_excl_pos|owned_land_pos)": 0.15155829077714103,
+  "P(shares_excl_pos|not owned_land_pos)": 0.16859099779208564,
+  "P(owned_land_pos&isa_pos)": 0.00046631199335324164,
+  "ratio_vs_indep(owned_land_pos,isa_pos)": 1.8754150093940034,
+  "P(isa_pos|owned_land_pos)": 0.23723677754206451,
+  "P(isa_pos|not owned_land_pos)": 0.12628018644840672,
+  "P(property_wealth_pos)": 0.6589250037325733,
+  "P(property_wealth_pos&pension_pos)": 0.5571833986840257,
+  "ratio_vs_indep(property_wealth_pos,pension_pos)": 1.1408255185540233,
+  "P(pension_pos|property_wealth_pos)": 0.8455945601210789,
+  "P(pension_pos|not property_wealth_pos)": 0.5395572125235916,
+  "P(property_wealth_pos&shares_excl_pos)": 0.1646804701791328,
+  "ratio_vs_indep(property_wealth_pos,shares_excl_pos)": 1.482716027087137,
+  "P(shares_excl_pos|property_wealth_pos)": 0.24992293393979148,
+  "P(shares_excl_pos|not property_wealth_pos)": 0.011367142742040188,
+  "P(property_wealth_pos&isa_pos)": 0.12056520593331854,
+  "ratio_vs_indep(property_wealth_pos,isa_pos)": 1.4464431722099018,
+  "P(isa_pos|property_wealth_pos)": 0.18297257692508248,
+  "P(isa_pos|not property_wealth_pos)": 0.017395225587018327,
+  "P(pension_pos)": 0.7412128729315728,
+  "P(pension_pos&shares_excl_pos)": 0.1542624998744278,
+  "ratio_vs_indep(pension_pos,shares_excl_pos)": 1.2347222750335949,
+  "P(shares_excl_pos|pension_pos)": 0.20812172252797476,
+  "P(shares_excl_pos|not pension_pos)": 0.05523852223622324,
+  "P(pension_pos&isa_pos)": 0.1175458693344547,
+  "ratio_vs_indep(pension_pos,isa_pos)": 1.2536600604161776,
+  "P(isa_pos|pension_pos)": 0.1585858444006089,
+  "P(isa_pos|not pension_pos)": 0.034593734249617494,
+  "P(shares_excl_pos)": 0.16855751834744545,
+  "P(shares_excl_pos&isa_pos)": 0.05973213266404448,
+  "ratio_vs_indep(shares_excl_pos,isa_pos)": 2.801400898486773,
+  "P(isa_pos|shares_excl_pos)": 0.3543724020717925,
+  "P(isa_pos|not shares_excl_pos)": 0.0803015857918814,
+  "P(isa_pos)": 0.12649828243548186,
+  "seconds": 1276.0
+ },
+ "D1_pension_first:fresh_seed_per_segment": {
+  "P(owned_land_pos)": 0.0015973632526921759,
+  "P(owned_land_pos&property_wealth_pos)": 0.0015973632526921759,
+  "ratio_vs_indep(owned_land_pos,property_wealth_pos)": 1.5098761783602952,
+  "P(property_wealth_pos|owned_land_pos)": 1.0,
+  "P(property_wealth_pos|not owned_land_pos)": 0.6617656823677158,
+  "P(owned_land_pos&pension_pos)": 0.0013844443337485213,
+  "ratio_vs_indep(owned_land_pos,pension_pos)": 1.164817932291937,
+  "P(pension_pos|owned_land_pos)": 0.8667060115569807,
+  "P(pension_pos|not owned_land_pos)": 0.7438737344368557,
+  "P(owned_land_pos&shares_excl_pos)": 0.000909661310198591,
+  "ratio_vs_indep(owned_land_pos,shares_excl_pos)": 3.5371755857077884,
+  "P(shares_excl_pos|owned_land_pos)": 0.5694767978826728,
+  "P(shares_excl_pos|not owned_land_pos)": 0.1603440714510367,
+  "P(owned_land_pos&isa_pos)": 0.0007956739252036313,
+  "ratio_vs_indep(owned_land_pos,isa_pos)": 4.223483498686684,
+  "P(isa_pos|owned_land_pos)": 0.49811708380207975,
+  "P(isa_pos|not owned_land_pos)": 0.11733161468468208,
+  "P(property_wealth_pos)": 0.6623059654375011,
+  "P(property_wealth_pos&pension_pos)": 0.5659089834417722,
+  "ratio_vs_indep(property_wealth_pos,pension_pos)": 1.1483496977307,
+  "P(pension_pos|property_wealth_pos)": 0.8544524932188227,
+  "P(pension_pos|not property_wealth_pos)": 0.5275810068472689,
+  "P(property_wealth_pos&shares_excl_pos)": 0.14792809326502496,
+  "ratio_vs_indep(property_wealth_pos,shares_excl_pos)": 1.3873069980410693,
+  "P(shares_excl_pos|property_wealth_pos)": 0.22335310413112122,
+  "P(shares_excl_pos|not property_wealth_pos)": 0.03870222873679029,
+  "P(property_wealth_pos&isa_pos)": 0.10961554698704633,
+  "ratio_vs_indep(property_wealth_pos,isa_pos)": 1.4033075229096037,
+  "P(isa_pos|property_wealth_pos)": 0.1655059031736749,
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+  "P(pension_pos)": 0.7440699422025718,
+  "P(pension_pos&shares_excl_pos)": 0.14817902031984218,
+  "ratio_vs_indep(pension_pos,shares_excl_pos)": 1.236953980820041,
+  "P(shares_excl_pos|pension_pos)": 0.19914662844894315,
+  "P(shares_excl_pos|not pension_pos)": 0.05008628069789383,
+  "P(pension_pos&isa_pos)": 0.1104765515918856,
+  "ratio_vs_indep(pension_pos,isa_pos)": 1.2589129866514228,
+  "P(isa_pos|pension_pos)": 0.14847603071407034,
+  "P(isa_pos|not pension_pos)": 0.029161544652293484,
+  "P(shares_excl_pos)": 0.16099760503371235,
+  "P(shares_excl_pos&isa_pos)": 0.05461090569975432,
+  "ratio_vs_indep(shares_excl_pos,isa_pos)": 2.876069181401818,
+  "P(isa_pos|shares_excl_pos)": 0.33920321788835917,
+  "P(isa_pos|not shares_excl_pos)": 0.07548126451176541,
+  "P(isa_pos)": 0.11793986740020936,
+  "seconds": 1757.9
+ },
+ "D2_shares_first:same_seed_per_segment(stage as-is)": {
+  "P(owned_land_pos)": 0.00196559740097869,
+  "P(owned_land_pos&property_wealth_pos)": 0.00196559740097869,
+  "ratio_vs_indep(owned_land_pos,property_wealth_pos)": 1.5176233931560639,
+  "P(property_wealth_pos|owned_land_pos)": 1.0,
+  "P(property_wealth_pos|not owned_land_pos)": 0.658253267242873,
+  "P(owned_land_pos&pension_pos)": 0.0009746705564756995,
+  "ratio_vs_indep(owned_land_pos,pension_pos)": 0.668350101335664,
+  "P(pension_pos|owned_land_pos)": 0.49586479713007436,
+  "P(pension_pos|not owned_land_pos)": 0.7424083308422835,
+  "P(owned_land_pos&shares_excl_pos)": 0.0011692906218771662,
+  "ratio_vs_indep(owned_land_pos,shares_excl_pos)": 3.9137745375500335,
+  "P(shares_excl_pos|owned_land_pos)": 0.5948779853366539,
+  "P(shares_excl_pos|not owned_land_pos)": 0.15112373498894455,
+  "P(owned_land_pos&isa_pos)": 0.0003240965753945136,
+  "ratio_vs_indep(owned_land_pos,isa_pos)": 1.2361621336152444,
+  "P(isa_pos|owned_land_pos)": 0.1648845156353701,
+  "P(isa_pos|not owned_land_pos)": 0.1333221760100451,
+  "P(property_wealth_pos)": 0.6589250037325733,
+  "P(property_wealth_pos&pension_pos)": 0.5540640092367449,
+  "ratio_vs_indep(property_wealth_pos,pension_pos)": 1.1333516813226265,
+  "P(pension_pos|property_wealth_pos)": 0.8408605017235216,
+  "P(pension_pos|not property_wealth_pos)": 0.5507871240410442,
+  "P(property_wealth_pos&shares_excl_pos)": 0.14211059347518623,
+  "ratio_vs_indep(property_wealth_pos,shares_excl_pos)": 1.418921507399471,
+  "P(shares_excl_pos|property_wealth_pos)": 0.21567036107323412,
+  "P(shares_excl_pos|not property_wealth_pos)": 0.028983020810954458,
+  "P(property_wealth_pos&isa_pos)": 0.12863443635850574,
+  "ratio_vs_indep(property_wealth_pos,isa_pos)": 1.4635812039973677,
+  "P(isa_pos|property_wealth_pos)": 0.19521862978311325,
+  "P(isa_pos|not property_wealth_pos)": 0.013925906490523065,
+  "P(pension_pos)": 0.7419237255131907,
+  "P(pension_pos&shares_excl_pos)": 0.1380483861486046,
+  "ratio_vs_indep(pension_pos,shares_excl_pos)": 1.2241650628035117,
+  "P(shares_excl_pos|pension_pos)": 0.18606816496280146,
+  "P(shares_excl_pos|not pension_pos)": 0.05404445282400248,
+  "P(pension_pos&isa_pos)": 0.12074941170340445,
+  "ratio_vs_indep(pension_pos,isa_pos)": 1.2201727661123043,
+  "P(isa_pos|pension_pos)": 0.16275178640483795,
+  "P(isa_pos|not pension_pos)": 0.04895763155486333,
+  "P(shares_excl_pos)": 0.15199597719010127,
+  "P(shares_excl_pos&isa_pos)": 0.057176770336181564,
+  "ratio_vs_indep(shares_excl_pos,isa_pos)": 2.8202206600142823,
+  "P(isa_pos|shares_excl_pos)": 0.37617291847580026,
+  "P(isa_pos|not shares_excl_pos)": 0.08986684317143111,
+  "P(isa_pos)": 0.13338421486278143,
+  "seconds": 1096.4
+ },
+ "D2_shares_first:fresh_seed_per_segment": {
+  "P(owned_land_pos)": 0.0015973632526921759,
+  "P(owned_land_pos&property_wealth_pos)": 0.0015973632526921759,
+  "ratio_vs_indep(owned_land_pos,property_wealth_pos)": 1.5098761783602952,
+  "P(property_wealth_pos|owned_land_pos)": 1.0,
+  "P(property_wealth_pos|not owned_land_pos)": 0.6617656823677158,
+  "P(owned_land_pos&pension_pos)": 0.001571638068171162,
+  "ratio_vs_indep(owned_land_pos,pension_pos)": 1.304785123022258,
+  "P(pension_pos|owned_land_pos)": 0.9838952195265185,
+  "P(pension_pos|not owned_land_pos)": 0.7536991523680879,
+  "P(owned_land_pos&shares_excl_pos)": 0.0005922878672022869,
+  "ratio_vs_indep(owned_land_pos,shares_excl_pos)": 2.421421382773783,
+  "P(shares_excl_pos|owned_land_pos)": 0.37079096830608343,
+  "P(shares_excl_pos|not owned_land_pos)": 0.15278122731631025,
+  "P(owned_land_pos&isa_pos)": 0.0008416337858327415,
+  "ratio_vs_indep(owned_land_pos,isa_pos)": 4.327119390484086,
+  "P(isa_pos|owned_land_pos)": 0.5268894125454949,
+  "P(isa_pos|not owned_land_pos)": 0.1211163060327941,
+  "P(property_wealth_pos)": 0.6623059654375011,
+  "P(property_wealth_pos&pension_pos)": 0.5633989056025666,
+  "ratio_vs_indep(property_wealth_pos,pension_pos)": 1.1280996853400094,
+  "P(pension_pos|property_wealth_pos)": 0.850662586483576,
+  "P(pension_pos|not property_wealth_pos)": 0.5646174761456335,
+  "P(property_wealth_pos&shares_excl_pos)": 0.14344728639004395,
+  "ratio_vs_indep(property_wealth_pos,shares_excl_pos)": 1.414408626290002,
+  "P(shares_excl_pos|property_wealth_pos)": 0.21658764057075436,
+  "P(shares_excl_pos|not property_wealth_pos)": 0.02867146198716859,
+  "P(property_wealth_pos&isa_pos)": 0.11361904301768104,
+  "ratio_vs_indep(property_wealth_pos,isa_pos)": 1.408873065502994,
+  "P(isa_pos|property_wealth_pos)": 0.17155068646049024,
+  "P(isa_pos|not property_wealth_pos)": 0.024120740169248284,
+  "P(pension_pos)": 0.754066859106681,
+  "P(pension_pos&shares_excl_pos)": 0.13870312468977797,
+  "ratio_vs_indep(pension_pos,shares_excl_pos)": 1.2012063430973448,
+  "P(shares_excl_pos|pension_pos)": 0.18394008835515613,
+  "P(shares_excl_pos|not pension_pos)": 0.05865961506089223,
+  "P(pension_pos&isa_pos)": 0.11376760358643971,
+  "ratio_vs_indep(pension_pos,isa_pos)": 1.2390480890624502,
+  "P(isa_pos|pension_pos)": 0.1508720376880328,
+  "P(isa_pos|not pension_pos)": 0.03251643705513199,
+  "P(shares_excl_pos)": 0.15312946806529623,
+  "P(shares_excl_pos&isa_pos)": 0.05476757708045537,
+  "ratio_vs_indep(shares_excl_pos,isa_pos)": 2.9372719673791416,
+  "P(isa_pos|shares_excl_pos)": 0.35765537340665104,
+  "P(isa_pos|not shares_excl_pos)": 0.07911114329194596,
+  "P(isa_pos)": 0.12176447308206823,
+  "seconds": 52.8
+ },
+ "elapsed_seconds": 4188.6
+}
diff --git a/experiments/452-uk-pension-wealth-split-receipt.json b/experiments/452-uk-pension-wealth-split-receipt.json
new file mode 100644
index 0000000000..6f78abce1d
--- /dev/null
+++ b/experiments/452-uk-pension-wealth-split-receipt.json
@@ -0,0 +1,934 @@
+{
+ "title": "UC caseload effect of splitting private pension wealth out of corporate_wealth (uk-data#452 mechanism M2)",
+ "date": "2026-08-23",
+ "method": "WAS wealth block re-imputed on every household of the released enhanced FRS h5 with the microcosm WAS stage code (clean_was_household_table -> impute_was_wealth -> support_clip_to_donor; seed 0; 100 trees), once with the pre-split arithmetic (OLD: pension inside corporate_wealth_excl_isa) and once with the split (NEW: private_pension_wealth drawn first in chain segment 2, share-like components conditional on it, segment 3 conditional on both); household wealth columns swapped into the single-year dataset before the simulation is built so stocks uprate 2024->2025 by the engine's registry; UC measured at 2025 with policyengine-uk 2.91.0 (c93e1a05); benefit-unit weights = the artifact's calibrated weights, unchanged.",
+ "artifact": {
+  "filename": "enhanced_frs_2024_25.h5",
+  "sha256": "e433e532b17bd8ce76030156285816e33d44e93edabd2204adbef71d19a68712",
+  "release": "policyengine-uk-data 1.56.16 (HF revision a9e52499)",
+  "dataset_year": 2024
+ },
+ "was_donor": {
+  "tab": "was_round_8_hhold_eul_may_2025_230525.tab",
+  "sha256": "18b3eb980c02c99f3d8a3254af859bee31682b2bdc11703877677292b3ce9374",
+  "households": 15128
+ },
+ "recipients": 52846,
+ "engine": "policyengine-uk 2.91.0 @ c93e1a05, policyengine-core 3.31.0",
+ "seed": 0,
+ "n_estimators": 100,
+ "year": 2025,
+ "donor_aggregates_weighted_bn": {
+  "total_private_pension_wealth_totalpen": 4807.7,
+  "current_db_dvvaldbt_scape": 1148.7,
+  "private_pension_wealth_remainder": 3659.0,
+  "share_like_corporate_wealth": 659.4,
+  "pension_share_of_old_corporate_wealth_mass": 0.847,
+  "negative_remainder_rows": 0
+ },
+ "draw_aggregates_2024": {
+  "incumbent": {
+   "owned_land": {
+    "weighted_total_bn": 397.625,
+    "nonzero_weighted_share": 0.0166,
+    "over_16k_weighted_share": 0.0152,
+    "weighted_mean_gbp": 12779.0
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+    "on_uc_not_reported_m": 2.0745,
+    "gb_housing_m": 4.6242,
+    "gb_lcwra_m": 2.1099,
+    "gb_carer_m": 0.6233,
+    "gb_childcare_m": 0.4099,
+    "gb_child_m": 2.8305,
+    "gb_housing_spend_bn": 34.364,
+    "gb_lcwra_spend_bn": 11.469,
+    "gb_carer_spend_bn": 1.508,
+    "gb_childcare_spend_bn": 1.793,
+    "gb_child_spend_bn": 17.671,
+    "gb_single_m": 3.0647,
+    "gb_lone_parent_m": 1.8972,
+    "gb_couple_no_children_m": 0.2792,
+    "gb_couple_with_children_m": 0.9223
+   }
+  }
+ },
+ "split_effect_new_minus_old": {
+  "uk_m": 1.073,
+  "gb_m": 1.0277,
+  "records": 1854,
+  "spend_bn": 8.607,
+  "eligible_m": 6.4852,
+  "eligible_unweighted": 12288,
+  "reporters_unweighted": 0,
+  "reporters_m": 0.0,
+  "reporters_over_16k_unweighted": -1408,
+  "reporters_over_16k_m": -0.7582,
+  "reporters_on_uc_m": 0.5142,
+  "reporters_not_on_uc_m": -0.5141,
+  "on_uc_not_reported_m": 0.5589,
+  "gb_housing_m": 0.5102,
+  "gb_lcwra_m": 0.3585,
+  "gb_carer_m": 0.0838,
+  "gb_childcare_m": 0.1428,
+  "gb_child_m": 0.5242,
+  "gb_housing_spend_bn": 3.933,
+  "gb_lcwra_spend_bn": 2.046,
+  "gb_carer_spend_bn": 0.203,
+  "gb_childcare_spend_bn": 0.571,
+  "gb_child_spend_bn": 3.338,
+  "gb_single_m": 0.4083,
+  "gb_lone_parent_m": 0.2658,
+  "gb_couple_no_children_m": 0.104,
+  "gb_couple_with_children_m": 0.2496
+ },
+ "split_effect_new_minus_old_anchored": {
+  "uk_m": 1.1225,
+  "gb_m": 1.0766,
+  "records": 1925,
+  "spend_bn": 8.945,
+  "eligible_m": 6.4852,
+  "eligible_unweighted": 12288,
+  "reporters_unweighted": 0,
+  "reporters_m": 0.0,
+  "reporters_over_16k_unweighted": -1408,
+  "reporters_over_16k_m": -0.7582,
+  "reporters_on_uc_m": 0.5637,
+  "reporters_not_on_uc_m": -0.5638,
+  "on_uc_not_reported_m": 0.5589,
+  "gb_housing_m": 0.544,
+  "gb_lcwra_m": 0.3953,
+  "gb_carer_m": 0.0846,
+  "gb_childcare_m": 0.1519,
+  "gb_child_m": 0.5367,
+  "gb_housing_spend_bn": 4.117,
+  "gb_lcwra_spend_bn": 2.233,
+  "gb_carer_spend_bn": 0.204,
+  "gb_childcare_spend_bn": 0.695,
+  "gb_child_spend_bn": 3.392,
+  "gb_single_m": 0.4419,
+  "gb_lone_parent_m": 0.2663,
+  "gb_couple_no_children_m": 0.107,
+  "gb_couple_with_children_m": 0.2614
+ },
+ "allocation_key_concentration_new_draw": {
+  "narrow": {
+   "mass_share_by_income_decile": [
+    0.1409,
+    0.0571,
+    0.0785,
+    0.0347,
+    0.1194,
+    0.0475,
+    0.0393,
+    0.1052,
+    0.1672,
+    0.2102
+   ],
+   "top10pct_households_share": 0.8672,
+   "top1pct_households_share": 0.2871,
+   "weighted_total_bn": 2499.183
+  },
+  "preserved": {
+   "mass_share_by_income_decile": [
+    0.0701,
+    0.0441,
+    0.0665,
+    0.0554,
+    0.097,
+    0.0804,
+    0.0889,
+    0.1298,
+    0.171,
+    0.1967
+   ],
+   "top10pct_households_share": 0.5441,
+   "top1pct_households_share": 0.1455,
+   "weighted_total_bn": 7604.734
+  }
+ },
+ "caveats": [
+  "Weights are the artifact's calibrated weights and are not recalibrated; the UK calibration surface now carries a UC caseload target (microcosm#735), which would absorb part of any move in a real build.",
+  "OLD and NEW are the same microcosm machinery at the same seed, so NEW-OLD isolates the arithmetic split; OLD is not the incumbent's own draw (microimpute 10-point quantile grid vs RegimeGatedQRF continuous quantile over the full leaf conditional) - the OLD re-draw sits 1.15m benefit units below the incumbent artifact on the same households, a draw-machinery/predictor-surface difference outside this change.",
+  "The recipient predictor surface is materialised from the released h5 (num_bedrooms is absent there, so the engine default 0 is used; incomes are the post-SPI h5 incomes), not from the FRS spine the build runs on.",
+  "SPI-synthetic clone households are re-imputed like any household.",
+  "private_pension_wealth is engine-unknown at policyengine-uk 2.91.0 and is ignored by the loader; the NEW numbers are the model-side-unchanged outcome (total_wealth and the exposure keys shrink there until the model PR lands).",
+  "Aggregates only (UKDS EUL); no unit records leave the licensed environment."
+ ],
+ "segment_seeds_from_declared_seed_0": [
+  3757552657,
+  673228719,
+  3241444873
+ ],
+ "per_segment_seed_fix": {
+  "what": "impute_was_wealth now derives one child seed per chain segment from the declared stage seed (SeedSequence(seed).spawn(3)); previously one RegimeGatedQRF was reused and start_chain respawned identical fit/draw streams per segment, coupling the k-th target of every segment.",
+  "hold_out_receipt_30_trees": {
+   "P(shares_excl_isa>0 | property_wealth=0)": {
+    "truth": 0.0551,
+    "stage_as_is_same_seed": 0.0114,
+    "production_child_seeds": 0.0387
+   },
+   "P(stocks_and_shares_isa>0 | property_wealth=0)": {
+    "truth": 0.0307,
+    "stage_as_is_same_seed": 0.0174,
+    "production_child_seeds": 0.0247
+   },
+   "P(private_pension_wealth>0 | property_wealth=0)": {
+    "truth": 0.5601,
+    "stage_as_is_same_seed": 0.5396,
+    "production_child_seeds": 0.5276
+   },
+   "source": "adversarial-review coupling check re-run with was_wealth_segment_seeds (the exact production derivation), train/hold-out halves of the donor, aggregates only; an earlier variant with modulo-2^31 seeds measured 0.045"
+  },
+  "uc_effect_new_with_fix_minus_new_without": {
+   "uk_m": 0.0026,
+   "gb_m": 0.0261,
+   "eligible_m": -0.6837,
+   "reporters_over_16k_m": -0.0425,
+   "gb_housing_m": -0.0061,
+   "gb_lcwra_m": 0.0023,
+   "gb_carer_m": -0.0226,
+   "gb_childcare_m": -0.002,
+   "gb_child_m": -0.0517,
+   "gb_single_m": 0.1332,
+   "gb_lone_parent_m": -0.0255,
+   "gb_couple_no_children_m": -0.0557,
+   "gb_couple_with_children_m": -0.026
+  }
+ },
+ "allocation_key_concentration_new_draw_per_segment_seeds": {
+  "narrow": {
+   "mass_share_by_income_decile": [
+    0.1138,
+    0.0227,
+    0.0277,
+    0.0379,
+    0.1059,
+    0.0595,
+    0.0761,
+    0.1036,
+    0.2016,
+    0.2512
+   ],
+   "top10pct_households_share": 0.8391,
+   "top1pct_households_share": 0.2669,
+   "weighted_total_bn": 1794.458
+  },
+  "preserved": {
+   "mass_share_by_income_decile": [
+    0.0461,
+    0.0516,
+    0.0372,
+    0.0475,
+    0.0719,
+    0.0803,
+    0.0939,
+    0.1298,
+    0.2014,
+    0.2404
+   ],
+   "top10pct_households_share": 0.5432,
+   "top1pct_households_share": 0.1354,
+   "weighted_total_bn": 7467.681
+  }
+ },
+ "fixed_draw_legal_counterfactual": {
+  "method": "On the final code's own draws (per-segment seeds), the drawn private_pension_wealth column is folded back into corporate_wealth on the SAME rows and UC recomputed: every draw identical, only the capital-test classification differs. Split minus folded is therefore the fixed-draw legal effect of the disregard (cross-family review design).",
+  "folded_back": {
+   "as_is": {
+    "uk_m": 4.8691,
+    "gb_m": 4.7612,
+    "records": 4584,
+    "spend_bn": 59.707,
+    "eligible_m": 8.6708,
+    "eligible_unweighted": 12690,
+    "reporters_unweighted": 6447,
+    "reporters_m": 5.9252,
+    "reporters_over_16k_unweighted": 3195,
+    "reporters_over_16k_m": 2.3732,
+    "reporters_on_uc_m": 3.385,
+    "reporters_not_on_uc_m": 2.5402,
+    "on_uc_not_reported_m": 1.4841,
+    "gb_housing_m": 3.7693,
+    "gb_lcwra_m": 1.7026,
+    "gb_carer_m": 0.5653,
+    "gb_childcare_m": 0.2352,
+    "gb_child_m": 2.2109,
+    "gb_housing_spend_bn": 27.806,
+    "gb_lcwra_spend_bn": 9.303,
+    "gb_carer_spend_bn": 1.368,
+    "gb_childcare_spend_bn": 1.029,
+    "gb_child_spend_bn": 13.764,
+    "gb_single_m": 2.3636,
+    "gb_lone_parent_m": 1.5224,
+    "gb_couple_no_children_m": 0.1916,
+    "gb_couple_with_children_m": 0.6837
+   },
+   "reporters_anchored": {
+    "uk_m": 4.889,
+    "gb_m": 4.7788,
+    "records": 4665,
+    "spend_bn": 59.835,
+    "eligible_m": 8.6708,
+    "eligible_unweighted": 12690,
+    "reporters_unweighted": 6447,
+    "reporters_m": 5.9252,
+    "reporters_over_16k_unweighted": 3195,
+    "reporters_over_16k_m": 2.3732,
+    "reporters_on_uc_m": 3.4049,
+    "reporters_not_on_uc_m": 2.5203,
+    "on_uc_not_reported_m": 1.4841,
+    "gb_housing_m": 3.774,
+    "gb_lcwra_m": 1.7062,
+    "gb_carer_m": 0.5656,
+    "gb_childcare_m": 0.2427,
+    "gb_child_m": 2.2187,
+    "gb_housing_spend_bn": 27.867,
+    "gb_lcwra_spend_bn": 9.322,
+    "gb_carer_spend_bn": 1.369,
+    "gb_childcare_spend_bn": 1.127,
+    "gb_child_spend_bn": 13.795,
+    "gb_single_m": 2.3693,
+    "gb_lone_parent_m": 1.5224,
+    "gb_couple_no_children_m": 0.1957,
+    "gb_couple_with_children_m": 0.6914
+   }
+  },
+  "split": {
+   "as_is": {
+    "uk_m": 6.2682,
+    "gb_m": 6.0898,
+    "records": 6591,
+    "spend_bn": 71.41,
+    "eligible_m": 15.5714,
+    "eligible_unweighted": 25009,
+    "reporters_unweighted": 6447,
+    "reporters_m": 5.9252,
+    "reporters_over_16k_unweighted": 1742,
+    "reporters_over_16k_m": 1.239,
+    "reporters_on_uc_m": 4.1938,
+    "reporters_not_on_uc_m": 1.7314,
+    "on_uc_not_reported_m": 2.0745,
+    "gb_housing_m": 4.586,
+    "gb_lcwra_m": 2.057,
+    "gb_carer_m": 0.6224,
+    "gb_childcare_m": 0.4007,
+    "gb_child_m": 2.817,
+    "gb_housing_spend_bn": 34.135,
+    "gb_lcwra_spend_bn": 11.201,
+    "gb_carer_spend_bn": 1.506,
+    "gb_childcare_spend_bn": 1.675,
+    "gb_child_spend_bn": 17.614,
+    "gb_single_m": 3.0129,
+    "gb_lone_parent_m": 1.8969,
+    "gb_couple_no_children_m": 0.2706,
+    "gb_couple_with_children_m": 0.9093
+   },
+   "reporters_anchored": {
+    "uk_m": 6.3449,
+    "gb_m": 6.1634,
+    "records": 6748,
+    "spend_bn": 71.915,
+    "eligible_m": 15.5714,
+    "eligible_unweighted": 25009,
+    "reporters_unweighted": 6447,
+    "reporters_m": 5.9252,
+    "reporters_over_16k_unweighted": 1742,
+    "reporters_over_16k_m": 1.239,
+    "reporters_on_uc_m": 4.2704,
+    "reporters_not_on_uc_m": 1.6547,
+    "on_uc_not_reported_m": 2.0745,
+    "gb_housing_m": 4.6242,
+    "gb_lcwra_m": 2.1099,
+    "gb_carer_m": 0.6233,
+    "gb_childcare_m": 0.4099,
+    "gb_child_m": 2.8305,
+    "gb_housing_spend_bn": 34.364,
+    "gb_lcwra_spend_bn": 11.469,
+    "gb_carer_spend_bn": 1.508,
+    "gb_childcare_spend_bn": 1.793,
+    "gb_child_spend_bn": 17.671,
+    "gb_single_m": 3.0647,
+    "gb_lone_parent_m": 1.8972,
+    "gb_couple_no_children_m": 0.2792,
+    "gb_couple_with_children_m": 0.9223
+   }
+  },
+  "fixed_draw_split_effect_as_is": {
+   "uk_m": 1.3991,
+   "gb_m": 1.3286,
+   "records": 2007,
+   "spend_bn": 11.703,
+   "eligible_m": 6.9006,
+   "eligible_unweighted": 12319,
+   "reporters_unweighted": 0,
+   "reporters_m": 0.0,
+   "reporters_over_16k_unweighted": -1453,
+   "reporters_over_16k_m": -1.1342,
+   "reporters_on_uc_m": 0.8088,
+   "reporters_not_on_uc_m": -0.8088,
+   "on_uc_not_reported_m": 0.5904,
+   "gb_housing_m": 0.8167,
+   "gb_housing_spend_bn": 6.329,
+   "gb_lcwra_m": 0.3544,
+   "gb_lcwra_spend_bn": 1.898,
+   "gb_carer_m": 0.0571,
+   "gb_carer_spend_bn": 0.138,
+   "gb_childcare_m": 0.1655,
+   "gb_childcare_spend_bn": 0.646,
+   "gb_child_m": 0.6061,
+   "gb_child_spend_bn": 3.85,
+   "gb_single_m": 0.6493,
+   "gb_lone_parent_m": 0.3745,
+   "gb_couple_no_children_m": 0.079,
+   "gb_couple_with_children_m": 0.2256
+  }
+ },
+ "note": "weights unchanged (incumbent calibrated weights); WAS wealth block re-imputed on all h5 households with microcosm's stage code and swapped into the dataset before build; aggregates only. The OLD/NEW redraw pair shares one seed pattern and is a whole-implementation comparison, not a fixed-draw effect - the fixed_draw_legal_counterfactual block is the causal number for the disregard itself.",
+ "microcosm_code_state": "branch uk-was-pension-wealth-split-452; receipts regenerated at the post-review commit (see git log)"
+}
diff --git a/experiments/452-uk-pension-wealth-split.md b/experiments/452-uk-pension-wealth-split.md
new file mode 100644
index 0000000000..9d3c9ada9a
--- /dev/null
+++ b/experiments/452-uk-pension-wealth-split.md
@@ -0,0 +1,167 @@
+# #750 / uk-data#452 (M2): private pension wealth split out of `corporate_wealth` — measurement receipt
+
+Committed receipt for the WAS-stage change that emits `private_pension_wealth`
+as its own household column and keeps `corporate_wealth` to the share-like
+holdings. Companion JSON: `452-uk-pension-wealth-split-receipt.json`
+(aggregates only — UKDS EUL; no unit records). Scripts and the full
+diagnosis live outside the repo (`~/PolicyEngine/_uk-defects-452-448/`,
+`measure/pension_split/`).
+
+## Why
+
+On the incumbent enhanced FRS (`enhanced_frs_2024_25.h5`, uk-data 1.56.14 /
+1.56.16) at 2025, 46% of benefit-unit records that report Universal Credit
+fail the £16,000 capital test, 96% of them on `corporate_wealth` alone. The
+WAS stage folds WAS private pension wealth less the current-employment DB
+component (`totalpenr8_aggr − dvvaldbt_scaper8_aggr`) into
+`corporate_wealth`, and the model counts that variable as UC capital. The
+value of a right to receive a pension under an occupational or personal
+pension scheme is disregarded capital (UC Regs 2013 Sch 10 para 10; HB Regs
+2006 Sch 6 paras 31–32 and HB(SPC) Regs 2006 Sch 6 para 24; JSA Regs 1996
+Sch 8 paras 28–29; ESA Regs 2008 Sch 9 paras 28–29; IS Regs 1987 Sch 10
+paras 23–23A; SPC Regs 2002 Sch V paras 22–23, Part I).
+
+## What the remainder is (donor, weighted £bn)
+
+WAS round 8 household tab (sha `18b3eb98…`, 15,128 households, 26.99m
+weighted): total private pension wealth 4,807.7; current-employment DB at
+the SCAPE rate 1,148.7; remainder 3,659.0 = current occupational DC 313.9 +
+AVCs 12.2 + retained DC 550.0 + current personal pensions 203.7 + retained
+DB 863.6 + pensions in payment 1,692.4 + expected from a former spouse 23.3
+(the ten-component identity is exact on 100% of rows; the remainder is never
+negative). Share-like holdings (employee shares, UK shares, unit and
+investment trusts, stocks-and-shares ISA) 659.4, so the pension component is
+84.7% of the old `corporate_wealth` mass. Hence the column is **not**
+DB-free (retained DB and DB pensions in payment stay inside it): it is named
+`private_pension_wealth` with the current-DB exclusion stated first in its
+documentation, not `non_db_pension_wealth`.
+
+## The fixed-draw legal effect (the causal number)
+
+On the final code's own draws (per-segment seeds, seed 0, 100 trees), the
+drawn `private_pension_wealth` column was folded back into `corporate_wealth`
+on the same rows and UC recomputed — every draw identical, only the
+capital-test classification differs. Split minus folded, 2025, weights
+unchanged:
+
+| | folded back (pension counted) | split (pension disregarded) | fixed-draw effect |
+|---|---|---|---|
+| UC benefit units, UK | 4.869 | 6.268 | **+1.399** |
+| UC benefit units, GB | 4.761 | 6.090 | +1.329 |
+| UC spend, £bn | 59.7 | 71.4 | +11.7 |
+| eligible benefit units | 8.67 | 15.57 | +6.90 |
+| reporter records over £16k | 3,195 | 1,742 | −1,453 |
+| GB housing / LCWRA / carer / childcare / child elements | 3.77 / 1.70 / 0.57 / 0.24 / 2.21 | 4.59 / 2.06 / 0.62 / 0.40 / 2.82 | +0.82 / +0.35 / +0.06 / +0.17 / +0.61 |
+| GB single / lone parent / couple no children / couple with children | 2.36 / 1.52 / 0.19 / 0.68 | 3.01 / 1.90 / 0.27 / 0.91 | +0.65 / +0.37 / +0.08 / +0.23 |
+
+With reporters anchored: 4.889 → 6.345 (+1.456).
+
+## Whole-implementation comparison (redraw pair, shared-seed variant)
+
+The WAS wealth block was re-imputed on every household of the 1.56.16
+artifact (seed 0, 100 trees), once with the pre-split arithmetic (OLD) and
+once with the split (NEW), both under the pre-fix shared-seed pattern, the
+household columns swapped into the single-year dataset before the simulation
+is built, and UC measured at 2025 with policyengine-uk 2.91.0. OLD and NEW
+are independently fitted and drawn, so this pair compares whole
+implementations rather than isolating the classification (the fixed-draw
+table above does that); no matched OLD′ exists for the final per-segment-seed
+branch. Benefit units in millions; GB = excluding Northern Ireland.
+
+| | incumbent artifact | OLD re-draw | NEW re-draw | NEW − OLD |
+|---|---|---|---|---|
+| UC benefit units, UK | 6.346 | 5.193 | 6.266 | **+1.073** |
+| UC benefit units, GB | 6.199 | 5.036 | 6.064 | +1.028 |
+| UC spend, £bn | 75.3 | 63.1 | 71.7 | +8.6 |
+| eligible benefit units (WA adult, capital ≤ £16k) | 10.52 | 9.77 | 16.26 | +6.49 |
+| reporter records over £16k (weighted m) | 2,958 (1.38) | 3,165 (2.04) | 1,757 (1.28) | −1,408 (−0.76) |
+| GB housing element | 4.868 | 4.082 | 4.592 | +0.510 |
+| GB LCWRA element | 2.102 | 1.696 | 2.055 | +0.359 |
+| GB carer element | 0.641 | 0.561 | 0.645 | +0.084 |
+| GB childcare element | 0.471 | 0.260 | 0.403 | +0.143 |
+| GB child element | 3.018 | 2.345 | 2.869 | +0.524 |
+| GB single | 2.969 | 2.471 | 2.880 | +0.408 |
+| GB lone parent | 2.135 | 1.657 | 1.922 | +0.266 |
+| GB couple, no children | 0.225 | 0.222 | 0.326 | +0.104 |
+| GB couple with children | 0.871 | 0.686 | 0.935 | +0.250 |
+
+With FRS reporters anchored (`would_claim_uc |= universal_credit_reported > 0`):
+OLD 5.217 → NEW 6.340 (UK), NEW′ 6.345. The incumbent's own upper bound (counterfactual
+C, `corporate_wealth` → 0 on the incumbent draws) is 6.881 UK.
+
+Allocation-key check on the NEW draw (why the model keeps
+`corporate_sector_wealth = corporate_wealth + private_pension_wealth` as the
+key for shareholding, corporate land value and the employer-NI capital
+response): the narrowed key puts 86.7% of its mass in the top 10% of
+households and 28.7% in the top 1% (preserved key: 54.4% / 14.6%).
+
+Regression receipt on the same run: chain segment 1 is untouched by the
+split, so the `owned_land` and `property_wealth` draws are identical OLD vs
+NEW at seed 0 (weighted totals 119.939 and 11,411.434 £bn in both); only the
+segment-2/3 columns move. On this re-draw the recipient-side `corporate_wealth`
+mass is 2,499 vs the incumbent's 9,149 £bn at 2024 (drift −0.73), inside the
+`uk_input_mass_parity` tolerance.
+
+Engine coupling: `private_pension_wealth` is engine-unknown until
+policyengine-uk publishes the companion variable; bump the `uk` extra lock to
+that release before any national build or calibration (the UK targets
+`ons.land.corporate_land_value` / `land_value` are materialised through the
+engine's `corporate_sector_wealth` key), and re-pin the `efrs-post-calibration`
+input-mass reference only after the uk-data mirror ships (re-pinning first
+would breach the gate on `corporate_wealth`).
+
+## Per-segment child seeds (review finding, second commit)
+
+`impute_was_wealth` reused one `RegimeGatedQRF` across its three chain
+segments, and `start_chain` respawns the fit and draw streams from the model
+seed on every call — so the k-th target of every segment consumed the same
+quantile and sign-gate uniforms per recipient, coupling `owned_land` with
+the first segment-2 target and `property_wealth` with the second (now the
+share-like holdings, the countable quantity). The adversarial review measured
+it on train/hold-out halves of the donor (30 trees; companion JSON
+`452-uk-pension-wealth-split-coupling-receipt.json`):
+
+| hold-out probability | observed | stage as-is (same seed) | production child seeds |
+|---|---|---|---|
+| P(shares excl. ISA > 0 \| property_wealth = 0) | 0.055 | 0.011 | 0.039 |
+| P(stocks-and-shares ISA > 0 \| property_wealth = 0) | 0.031 | 0.017 | 0.025 |
+| P(private pension wealth > 0 \| property_wealth = 0) | 0.560 | 0.540 | 0.528 |
+
+(The receipt was re-run with `was_wealth_segment_seeds` — the exact production
+derivation — after review caught that the first variant derived its child
+seeds with a modulo-2^31 truncation and measured 0.045; the unit test now
+golden-pins the production tuple.)
+
+The stage now derives one child seed per segment from the declared seed
+(`SeedSequence(0).spawn(3)` → 3757552657, 673228719, 3241444873); the
+declared `fit_weighted_qrf_chain.seed: 0` stays the root and the spec digest
+is unchanged (the note is documentation). Re-measured with the fix (NEW′):
+UC benefit units 6.268m UK (vs 6.266m without the fix), eligible 15.57m (vs
+16.26m), reporter records over £16k 1,742 (vs 1,757); GB elements within
+±0.05m except singles +0.13m and couples without children −0.06m. The
+caseload effect of the split is unchanged; the fix corrects who holds the
+countable assets. Seed-to-seed swings in the tail-dominated totals
+(`corporate_wealth` 2,499 → 1,794 £bn, `savings` 1,489 → 899 £bn at 2024 for
+the two draws) are the stage's known realisation variance (cf. the
+`owned_land` exclusion receipt), not an effect of either change.
+
+## Caveats (travel with the numbers)
+
+- Weights are not recalibrated; the UK surface now compiles a UC caseload
+  target (microcosm#735), which absorbs part of any move in a real build.
+- OLD is not the incumbent's own draw: this package draws a continuous
+  quantile over the full leaf conditional, the incumbent's microimpute QRF a
+  random point on a 10-quantile grid, and the predictor surface here is the
+  released h5 (no `num_bedrooms`, post-SPI incomes), not the FRS spine. On
+  the same households the OLD re-draw sits 1.15m benefit units below the
+  incumbent artifact — a draw-machinery difference outside this change and
+  worth its own look (the re-draw also carries lower savings / other-property
+  mass than the incumbent and higher property wealth).
+- `private_pension_wealth` is engine-unknown at 2.91.0, so the NEW numbers
+  are the model-side-unchanged outcome; the policyengine-uk companion PR
+  makes the disregard explicit and keeps `total_wealth` and the exposure
+  keys whole.
+- `uk_input_mass_parity` will report `corporate_wealth` at roughly −0.85
+  against the incumbent reference (pension mass moved to a column the
+  reference lacks); inside the armed tolerance (4.52), so no exclusion
+  receipt is added — the drift is explained here.
diff --git a/packages/microcosm-build/src/microcosm/build/uk/gates.json b/packages/microcosm-build/src/microcosm/build/uk/gates.json
index ed3447dab5..09ae60a691 100644
--- a/packages/microcosm-build/src/microcosm/build/uk/gates.json
+++ b/packages/microcosm-build/src/microcosm/build/uk/gates.json
@@ -526,6 +526,7 @@
           "household.msoa_code",
           "household.num_vehicles",
           "household.oa_code",
+          "household.private_pension_wealth",
           "household.property_purchased",
           "household.rail_usage",
           "household.region_code_oa",
diff --git a/packages/microcosm-build/src/microcosm/build/uk/release_input_coverage_manifest.json b/packages/microcosm-build/src/microcosm/build/uk/release_input_coverage_manifest.json
index 92b351673d..a84f49346e 100644
--- a/packages/microcosm-build/src/microcosm/build/uk/release_input_coverage_manifest.json
+++ b/packages/microcosm-build/src/microcosm/build/uk/release_input_coverage_manifest.json
@@ -473,7 +473,7 @@
     "capital_gains"
    ],
    "source_manifest": "source_stages.json",
-   "source_manifest_sha256": "84d1c1c85f0172a9a396ef69d445ee33cf1340f62ff73c8653c399af40087bf4",
+   "source_manifest_sha256": "b04f5c9af88d5c6e11e687daa1c7eb382058e3ed4f637e1075887f4f7cc043e3",
    "source_vintages": {
     "source": "HMRC Capital Gains Tax statistics, July 2025, Table 2.1a",
     "survey": "HMRC Capital Gains Tax statistics Table 2.1a and Advani-Summers capital-gains incidence"
@@ -496,7 +496,7 @@
     "capital_gains"
    ],
    "source_manifest": "source_stages.json",
-   "source_manifest_sha256": "84d1c1c85f0172a9a396ef69d445ee33cf1340f62ff73c8653c399af40087bf4",
+   "source_manifest_sha256": "b04f5c9af88d5c6e11e687daa1c7eb382058e3ed4f637e1075887f4f7cc043e3",
    "source_vintages": {
     "source": "Advani and Summers (2020), Capital Gains and UK Inequality, CAGE Working Paper 465",
     "survey": "Family Resources Survey 2024-25, SPI synthetic support, and Advani-Summers capital-gains incidence"
@@ -525,7 +525,7 @@
    "required_mass_change_reason": "E5 source-stage transform preserves household rows and typed household weights; total household mass is conserved.",
    "rewrites": [],
    "source_manifest": "source_stages.json",
-   "source_manifest_sha256": "84d1c1c85f0172a9a396ef69d445ee33cf1340f62ff73c8653c399af40087bf4",
+   "source_manifest_sha256": "b04f5c9af88d5c6e11e687daa1c7eb382058e3ed4f637e1075887f4f7cc043e3",
    "source_vintages": {
     "source": "UK Data Service SN 8856 Effects of Taxes and Benefits household tab, DfT rail fare index, and public NHS activity/cost table.",
     "survey": "Effects of Taxes and Benefits 1977-2024 and NHS age-gender public table"
@@ -545,7 +545,7 @@
    "required_mass_change_reason": "E5 source-stage transform preserves household rows and typed household weights; total household mass is conserved.",
    "rewrites": [],
    "source_manifest": "source_stages.json",
-   "source_manifest_sha256": "84d1c1c85f0172a9a396ef69d445ee33cf1340f62ff73c8653c399af40087bf4",
+   "source_manifest_sha256": "b04f5c9af88d5c6e11e687daa1c7eb382058e3ed4f637e1075887f4f7cc043e3",
    "source_vintages": {
     "source": "UK Data Service SN 8856 Effects of Taxes and Benefits household tab and cited VAT anchor resource.",
     "survey": "Effects of Taxes and Benefits 1977-2024"
@@ -565,20 +565,20 @@
     "capital_gains"
    ],
    "required_mass_change_reason": "Amounts-only capital gains redraw: household weights pass through unchanged and total household mass is conserved.",
-    "source_manifest": "cgt_source_stages.json",
-    "source_manifest_sha256": "71104111b4b9f2da00ce49ad5abec54a35d300196032c9742d62e02aa1730774",
-    "superseded_by": {
-      "reason": "The FRS spine build executes hmrc_cgt_gains_spine, which applies the same HMRC Table 3 amounts redraw directly in source_stages.json before calibration.",
-      "source_manifest": "source_stages.json",
-      "source_manifest_sha256": "84d1c1c85f0172a9a396ef69d445ee33cf1340f62ff73c8653c399af40087bf4",
-      "stage": "hmrc_cgt_gains_spine"
-    },
-    "source_vintages": {
-      "hmrc_surface": "2023-24",
-      "mapped_build_period": "2024"
+   "source_manifest": "cgt_source_stages.json",
+   "source_manifest_sha256": "71104111b4b9f2da00ce49ad5abec54a35d300196032c9742d62e02aa1730774",
+   "source_vintages": {
+    "hmrc_surface": "2023-24",
+    "mapped_build_period": "2024"
    },
    "stage": "hmrc_cgt_gains",
-   "status": "required_at_build"
+   "status": "required_at_build",
+   "superseded_by": {
+    "reason": "The FRS spine build executes hmrc_cgt_gains_spine, which applies the same HMRC Table 3 amounts redraw directly in source_stages.json before calibration.",
+    "source_manifest": "source_stages.json",
+    "source_manifest_sha256": "b04f5c9af88d5c6e11e687daa1c7eb382058e3ed4f637e1075887f4f7cc043e3",
+    "stage": "hmrc_cgt_gains_spine"
+   }
   },
   "hmrc_cgt_gains_spine": {
    "base_candidate_sha256": "f17306ccb2aad7ff0130be3589b560afb2e2a12a943570911cd0c77f07934833",
@@ -596,7 +596,7 @@
     "capital_gains"
    ],
    "source_manifest": "source_stages.json",
-   "source_manifest_sha256": "84d1c1c85f0172a9a396ef69d445ee33cf1340f62ff73c8653c399af40087bf4",
+   "source_manifest_sha256": "b04f5c9af88d5c6e11e687daa1c7eb382058e3ed4f637e1075887f4f7cc043e3",
    "source_vintages": {
     "hmrc_surface": "2023-24",
     "mapped_build_period": "2024"
@@ -610,7 +610,7 @@
    "base_candidate_tier": "frs",
    "calibration_permitted": false,
    "canonical_source_manifest": "source_stages.json",
-   "canonical_source_manifest_sha256": "84d1c1c85f0172a9a396ef69d445ee33cf1340f62ff73c8653c399af40087bf4",
+   "canonical_source_manifest_sha256": "b04f5c9af88d5c6e11e687daa1c7eb382058e3ed4f637e1075887f4f7cc043e3",
    "effective_mass_requirements": {
     "charitable_investment_gifts": {
      "mass_share_denominator": "all_person_effective_mass",
@@ -669,7 +669,7 @@
      "OTHERINC"
     ]
    },
-    "reviewed_fence_ids": [
+   "reviewed_fence_ids": [
     "frs_epb_source_absent",
     "frs_exps_source_absent",
     "frs_taxterm_source_absent",
@@ -679,15 +679,9 @@
     "frs_srp_regular_code5_subset",
     "full_frs_tei_band_unavailable"
    ],
-    "source_manifest": "hmrc_income_source_stages.json",
-    "source_manifest_sha256": "c0341af7166ae3a85a3c1164e7d9e880c4b4aec122f1a8fa90c73b46c596e1ea",
-    "superseded_by": {
-      "reason": "The FRS spine build executes hmrc_spi_income_spine, which supersedes the June retained-leaves/hmrc_spi_income pair inside source_stages.json.",
-      "source_manifest": "source_stages.json",
-      "source_manifest_sha256": "84d1c1c85f0172a9a396ef69d445ee33cf1340f62ff73c8653c399af40087bf4",
-      "stage": "hmrc_spi_income_spine"
-    },
-    "source_vintages": {
+   "source_manifest": "hmrc_income_source_stages.json",
+   "source_manifest_sha256": "c0341af7166ae3a85a3c1164e7d9e880c4b4aec122f1a8fa90c73b46c596e1ea",
+   "source_vintages": {
     "hmrc_surface": "2023-24",
     "mapped_build_period": "2024",
     "period_mapping": "latest_published_tax_year",
@@ -695,7 +689,13 @@
    },
    "spi_prior_national_household_mass_share": 0.5,
    "stage": "hmrc_spi_income",
-   "status": "required_at_build"
+   "status": "required_at_build",
+   "superseded_by": {
+    "reason": "The FRS spine build executes hmrc_spi_income_spine, which supersedes the June retained-leaves/hmrc_spi_income pair inside source_stages.json.",
+    "source_manifest": "source_stages.json",
+    "source_manifest_sha256": "b04f5c9af88d5c6e11e687daa1c7eb382058e3ed4f637e1075887f4f7cc043e3",
+    "stage": "hmrc_spi_income_spine"
+   }
   },
   "lcfs_consumption": {
    "base_candidate_sha256": "f17306ccb2aad7ff0130be3589b560afb2e2a12a943570911cd0c77f07934833",
@@ -727,7 +727,7 @@
    "required_mass_change_reason": "E5 source-stage transform preserves household rows and typed household weights; total household mass is conserved.",
    "rewrites": [],
    "source_manifest": "source_stages.json",
-   "source_manifest_sha256": "84d1c1c85f0172a9a396ef69d445ee33cf1340f62ff73c8653c399af40087bf4",
+   "source_manifest_sha256": "b04f5c9af88d5c6e11e687daa1c7eb382058e3ed4f637e1075887f4f7cc043e3",
    "source_vintages": {
     "source": "UK Data Service SN 9468 Living Costs and Food Survey 2023-24 household/person tabs, NEED 2023 headline energy tables, Ofgem Q2 2026 unit rates, and WAS round-8 bridge donor.",
     "survey": "Living Costs and Food Survey 2023-24"
@@ -748,7 +748,7 @@
     "property_wealth"
    ],
    "source_manifest": "source_stages.json",
-   "source_manifest_sha256": "84d1c1c85f0172a9a396ef69d445ee33cf1340f62ff73c8653c399af40087bf4",
+   "source_manifest_sha256": "b04f5c9af88d5c6e11e687daa1c7eb382058e3ed4f637e1075887f4f7cc043e3",
    "source_vintages": {
     "source": "MHCLG dwellings and ONS UK House Price Index December 2025 regional average prices.",
     "survey": "Public regional property reference"
@@ -772,7 +772,7 @@
     "employee_pension_contributions"
    ],
    "source_manifest": "source_stages.json",
-   "source_manifest_sha256": "84d1c1c85f0172a9a396ef69d445ee33cf1340f62ff73c8653c399af40087bf4",
+   "source_manifest_sha256": "b04f5c9af88d5c6e11e687daa1c7eb382058e3ed4f637e1075887f4f7cc043e3",
    "source_vintages": {
     "source": "HMRC, Salary sacrifice reform for pension contributions effective from 6 April 2029",
     "survey": "Family Resources Survey 2024-25 salary-sacrifice respondents and HMRC salary-sacrifice reform analysis"
@@ -794,7 +794,7 @@
     "student_loan_plan"
    ],
    "source_manifest": "source_stages.json",
-   "source_manifest_sha256": "84d1c1c85f0172a9a396ef69d445ee33cf1340f62ff73c8653c399af40087bf4",
+   "source_manifest_sha256": "b04f5c9af88d5c6e11e687daa1c7eb382058e3ed4f637e1075887f4f7cc043e3",
    "source_vintages": {
     "source": "Explore Education Statistics Table 6a, Higher education total",
     "survey": "Family Resources Survey 2024-25 and Student Loans Company borrower forecasts for England"
@@ -812,6 +812,7 @@
     "owned_land",
     "property_wealth",
     "corporate_wealth",
+    "private_pension_wealth",
     "gross_financial_wealth",
     "net_financial_wealth",
     "main_residence_value",
@@ -826,7 +827,7 @@
    "required_mass_change_reason": "E5 source-stage transform preserves household rows and typed household weights; total household mass is conserved.",
    "rewrites": [],
    "source_manifest": "source_stages.json",
-   "source_manifest_sha256": "84d1c1c85f0172a9a396ef69d445ee33cf1340f62ff73c8653c399af40087bf4",
+   "source_manifest_sha256": "b04f5c9af88d5c6e11e687daa1c7eb382058e3ed4f637e1075887f4f7cc043e3",
    "source_vintages": {
     "source": "Office for National Statistics Wealth and Assets Survey, UK Data Service SN 7215, DOI 10.5255/UKDA-SN-7215-20; local licensed 2006-22 household tab.",
     "survey": "Wealth and Assets Survey round 8"
diff --git a/packages/microcosm-build/src/microcosm/build/uk/source_stages.json b/packages/microcosm-build/src/microcosm/build/uk/source_stages.json
index 2741736236..7d206dca19 100644
--- a/packages/microcosm-build/src/microcosm/build/uk/source_stages.json
+++ b/packages/microcosm-build/src/microcosm/build/uk/source_stages.json
@@ -907,7 +907,8 @@
       "weight": "R8xshhwgt"
      },
      "derived": {
-      "corporate_wealth_excl_isa": "(totalpenr8_aggr - dvvaldbt_scaper8_aggr) + DVFESHARESR8_aggr + DVFShUKVR8_aggr + DVFCollVR8_aggr",
+      "private_pension_wealth": "totalpenr8_aggr - dvvaldbt_scaper8_aggr",
+      "corporate_wealth_excl_isa": "DVFESHARESR8_aggr + DVFShUKVR8_aggr + DVFCollVR8_aggr",
       "stocks_and_shares_isa": "DVIISAVR8_aggr",
       "cash_isa": "DVCISAVR8_aggr",
       "student_loan_balance": "Tot_LosR8_aggr - Tot_los_exc_SLCR8_aggr",
@@ -960,6 +961,7 @@
      "chain_order": [
       "owned_land",
       "property_wealth",
+      "private_pension_wealth",
       "corporate_wealth_excl_isa",
       "stocks_and_shares_isa",
       "corporate_wealth",
@@ -1008,6 +1010,7 @@
     "owned_land",
     "property_wealth",
     "corporate_wealth",
+    "private_pension_wealth",
     "gross_financial_wealth",
     "net_financial_wealth",
     "main_residence_value",
@@ -1023,6 +1026,7 @@
     "owned_land",
     "property_wealth",
     "corporate_wealth",
+    "private_pension_wealth",
     "gross_financial_wealth",
     "main_residence_value",
     "other_residential_property_value",
@@ -1033,7 +1037,7 @@
     "stocks_and_shares_isa",
     "student_loan_balance"
    ],
-   "notes": "Ports incumbent WAS round-8 wealth imputation with signed E5 differences: exact lower-case column matching replaces the fuzzy r/w fallback; cash ISA uses DVCISAVR8_aggr and stocks-and-shares ISA uses DVIISAVR8_aggr; corporate_wealth folds stocks-and-shares ISA after drawing corporate_wealth_excl_isa; recipient Northern Ireland regions are mapped to Wales for prediction only; student_loan_balance is allocated by household id rather than the incumbent positional off-by-one. Engine predictors materialize at their native entity and person/benunit values are summed to household, reproducing the incumbent map_to=household semantics; region is one-hot encoded jointly across donor and recipient (the incumbent's dummy encoding), with unmapped donor GOR codes becoming all-zero dummy rows. The WAS and FRS predictor definitions are not fully like-for-like and are ported as-is; raw WAS missing values are blanket-filled with zero; UKDS negative sentinel codes (-9/-8/-7/-6) are recoded to zero for the nonnegative-domain columns the licensed audit found carrying them (vcarnr8: 2 rows; HBedRmR8: 95.8 percent - the bedrooms question is effectively unasked in the WAS household file, predictor-quality revisit registered on microcosm#145) - a signed difference vs the incumbent, which trains on raw sentinels; DVPriRntR8's -9 is structural not-applicable so the is_renting mapping is unchanged; genuinely negative domains are never recoded."
+   "notes": "Ports incumbent WAS round-8 wealth imputation with signed E5 differences: exact lower-case column matching replaces the fuzzy r/w fallback; cash ISA uses DVCISAVR8_aggr and stocks-and-shares ISA uses DVIISAVR8_aggr; private pension wealth (WAS total private pension wealth less the current defined-benefit component; DB-type components at the SCAPE rate, money-purchase components at reported fund values) is drawn as its own output private_pension_wealth and no longer folded into corporate_wealth, which keeps only the share-like holdings - pension rights are disregarded capital in every means test (UC Regs 2013 Sch 10 para 10 and the HB/JSA/ESA/IS/SPC parallels; uk-data#452) - and the downstream chain segment conditions on both components; each chain segment starts its own fit and draw RNG streams from a child seed derived deterministically from the declared seed (start_chain respawns from the model seed on every call, so one shared model coupled the k-th target of every segment); corporate_wealth folds stocks-and-shares ISA after drawing corporate_wealth_excl_isa; recipient Northern Ireland regions are mapped to Wales for prediction only; student_loan_balance is allocated by household id rather than the incumbent positional off-by-one. Engine predictors materialize at their native entity and person/benunit values are summed to household, reproducing the incumbent map_to=household semantics; region is one-hot encoded jointly across donor and recipient (the incumbent's dummy encoding), with unmapped donor GOR codes becoming all-zero dummy rows. The WAS and FRS predictor definitions are not fully like-for-like and are ported as-is; raw WAS missing values are blanket-filled with zero; UKDS negative sentinel codes (-9/-8/-7/-6) are recoded to zero for the nonnegative-domain columns the licensed audit found carrying them (vcarnr8: 2 rows; HBedRmR8: 95.8 percent - the bedrooms question is effectively unasked in the WAS household file, predictor-quality revisit registered on microcosm#145) - a signed difference vs the incumbent, which trains on raw sentinels; DVPriRntR8's -9 is structural not-applicable so the is_renting mapping is unchanged; genuinely negative domains are never recoded."
   },
   {
    "stage": "regional_property_uprating",
diff --git a/packages/microcosm-build/src/microcosm/build/uk/spec/sources.yaml b/packages/microcosm-build/src/microcosm/build/uk/spec/sources.yaml
index d30a94190b..c7054e4f5a 100644
--- a/packages/microcosm-build/src/microcosm/build/uk/spec/sources.yaml
+++ b/packages/microcosm-build/src/microcosm/build/uk/spec/sources.yaml
@@ -724,7 +724,8 @@ stages:
       num_vehicles: vcarnr8
       weight: R8xshhwgt
     derived:
-      corporate_wealth_excl_isa: (totalpenr8_aggr - dvvaldbt_scaper8_aggr) + DVFESHARESR8_aggr + DVFShUKVR8_aggr + DVFCollVR8_aggr
+      private_pension_wealth: totalpenr8_aggr - dvvaldbt_scaper8_aggr
+      corporate_wealth_excl_isa: DVFESHARESR8_aggr + DVFShUKVR8_aggr + DVFCollVR8_aggr
       stocks_and_shares_isa: DVIISAVR8_aggr
       cash_isa: DVCISAVR8_aggr
       student_loan_balance: Tot_LosR8_aggr - Tot_los_exc_SLCR8_aggr
@@ -767,6 +768,7 @@ stages:
     chain_order:
     - owned_land
     - property_wealth
+    - private_pension_wealth
     - corporate_wealth_excl_isa
     - stocks_and_shares_isa
     - corporate_wealth
@@ -803,6 +805,7 @@ stages:
   - owned_land
   - property_wealth
   - corporate_wealth
+  - private_pension_wealth
   - gross_financial_wealth
   - net_financial_wealth
   - main_residence_value
@@ -817,6 +820,7 @@ stages:
   - owned_land
   - property_wealth
   - corporate_wealth
+  - private_pension_wealth
   - gross_financial_wealth
   - main_residence_value
   - other_residential_property_value
@@ -826,7 +830,7 @@ stages:
   - cash_isa
   - stocks_and_shares_isa
   - student_loan_balance
-  notes: 'Ports incumbent WAS round-8 wealth imputation with signed E5 differences: exact lower-case column matching replaces the fuzzy r/w fallback; cash ISA uses DVCISAVR8_aggr and stocks-and-shares ISA uses DVIISAVR8_aggr; corporate_wealth folds stocks-and-shares ISA after drawing corporate_wealth_excl_isa; recipient Northern Ireland regions are mapped to Wales for prediction only; student_loan_balance is allocated by household id rather than the incumbent positional off-by-one. Engine predictors materialize at their native entity and person/benunit values are summed to household, reproducing the incumbent map_to=household semantics; region is one-hot encoded jointly across donor and recipient (the incumbent''s dummy encoding), with unmapped donor GOR codes becoming all-zero dummy rows. The WAS and FRS predictor definitions are not fully like-for-like and are ported as-is; raw WAS missing values are blanket-filled with zero; UKDS negative sentinel codes (-9/-8/-7/-6) are recoded to zero
+  notes: 'Ports incumbent WAS round-8 wealth imputation with signed E5 differences: exact lower-case column matching replaces the fuzzy r/w fallback; cash ISA uses DVCISAVR8_aggr and stocks-and-shares ISA uses DVIISAVR8_aggr; private pension wealth (WAS total private pension wealth less the current defined-benefit component; DB-type components at the SCAPE rate, money-purchase components at reported fund values) is drawn as its own output private_pension_wealth and no longer folded into corporate_wealth, which keeps only the share-like holdings - pension rights are disregarded capital in every means test (UC Regs 2013 Sch 10 para 10 and the HB/JSA/ESA/IS/SPC parallels; uk-data#452) - and the downstream chain segment conditions on both components; each chain segment starts its own fit and draw RNG streams from a child seed derived deterministically from the declared seed (start_chain respawns from the model seed on every call, so one shared model coupled the k-th target of every segment); corporate_wealth folds stocks-and-shares ISA after drawing corporate_wealth_excl_isa; recipient Northern Ireland regions are mapped to Wales for prediction only; student_loan_balance is allocated by household id rather than the incumbent positional off-by-one. Engine predictors materialize at their native entity and person/benunit values are summed to household, reproducing the incumbent map_to=household semantics; region is one-hot encoded jointly across donor and recipient (the incumbent''s dummy encoding), with unmapped donor GOR codes becoming all-zero dummy rows. The WAS and FRS predictor definitions are not fully like-for-like and are ported as-is; raw WAS missing values are blanket-filled with zero; UKDS negative sentinel codes (-9/-8/-7/-6) are recoded to zero
     for the nonnegative-domain columns the licensed audit found carrying them (vcarnr8: 2 rows; HBedRmR8: 95.8 percent - the bedrooms question is effectively unasked in the WAS household file, predictor-quality revisit registered on microcosm#145) - a signed difference vs the incumbent, which trains on raw sentinels; DVPriRntR8''s -9 is structural not-applicable so the is_renting mapping is unchanged; genuinely negative domains are never recoded.'
 - stage: regional_property_uprating
   survey: Public regional property reference
diff --git a/packages/microcosm-build/src/microcosm/build/uk/was_wealth_support_bounds.json b/packages/microcosm-build/src/microcosm/build/uk/was_wealth_support_bounds.json
index 0d9bce9bd4..1cc3475e7b 100644
--- a/packages/microcosm-build/src/microcosm/build/uk/was_wealth_support_bounds.json
+++ b/packages/microcosm-build/src/microcosm/build/uk/was_wealth_support_bounds.json
@@ -22,6 +22,10 @@
       0.0,
       30000000
     ],
+    "private_pension_wealth": [
+      0.0,
+      8000000
+    ],
     "gross_financial_wealth": [
       0.0,
       30000000
diff --git a/packages/microcosm-build/src/microcosm/build/uk_runtime/terminal_gates.py b/packages/microcosm-build/src/microcosm/build/uk_runtime/terminal_gates.py
index 625d96028e..1e4660caf8 100644
--- a/packages/microcosm-build/src/microcosm/build/uk_runtime/terminal_gates.py
+++ b/packages/microcosm-build/src/microcosm/build/uk_runtime/terminal_gates.py
@@ -178,6 +178,7 @@ def __post_init__(self) -> None:
     "household.msoa_code",
     "household.num_vehicles",
     "household.oa_code",
+    "household.private_pension_wealth",
     "household.property_purchased",
     "household.rail_usage",
     "household.region_code_oa",
diff --git a/packages/microcosm-build/src/microcosm/build/uk_runtime/was_wealth.py b/packages/microcosm-build/src/microcosm/build/uk_runtime/was_wealth.py
index 27a1b8d038..1a3879f7f9 100644
--- a/packages/microcosm-build/src/microcosm/build/uk_runtime/was_wealth.py
+++ b/packages/microcosm-build/src/microcosm/build/uk_runtime/was_wealth.py
@@ -59,6 +59,7 @@
     "owned_land",
     "property_wealth",
     "corporate_wealth",
+    "private_pension_wealth",
     "gross_financial_wealth",
     "net_financial_wealth",
     "main_residence_value",
@@ -283,10 +284,20 @@ def clean_was_household_table(raw: pd.DataFrame) -> pd.DataFrame:
         values = cleaned[column]
         cleaned[column] = values.where(~values.isin(_SENTINEL_CODES), 0)
     cleaned["is_renting"] = cleaned["private_rent_code"] == 1
+    # Private pension wealth other than current-employment defined-benefit
+    # entitlements (WAS total private pension wealth less DVValDBT_SCAPE;
+    # defined-benefit-type components are valued at the SCAPE discount rate,
+    # money-purchase components are reported fund values): DC pots, AVCs,
+    # current personal pensions, retained DB/DC rights, pensions in payment
+    # and pensions expected from a former spouse or partner.
+    # The incumbent folds this into corporate_wealth, where the means-tested
+    # capital tests count it; pension rights are disregarded capital (UC Regs
+    # 2013 Sch 10 para 10 and the parallel HB/JSA/ESA/IS/SPC paragraphs), so
+    # the stage emits it as its own column and keeps corporate_wealth to the
+    # share-like holdings (uk-data#452).
+    cleaned["private_pension_wealth"] = cleaned["pensions"] - cleaned["db_pensions"]
     cleaned["corporate_wealth_excl_isa"] = (
-        cleaned["pensions"]
-        - cleaned["db_pensions"]
-        + cleaned["emp_shares_options"]
+        cleaned["emp_shares_options"]
         + cleaned["uk_shares"]
         + cleaned["unit_investment_trusts"]
     )
@@ -376,6 +387,27 @@ class UKWASWealthImputationResult:
 
     draws: pd.DataFrame
     fit_weight_records: tuple[FitWeightRecord, ...]
+    #: The per-segment RNG roots derived from the declared stage seed.
+    segment_seeds: tuple[int, ...] = ()
+
+
+def was_wealth_segment_seeds(seed: int, segments: int = 3) -> tuple[int, ...]:
+    """Derive one independent RNG root per chain segment from the stage seed.
+
+    :meth:`RegimeGatedQRF.start_chain` spawns its fit and draw streams from
+    the model seed on every call, so one model reused across segments would
+    restart the same streams each time and couple the k-th target of every
+    segment (the same quantile and sign-gate uniforms per recipient). On the
+    licensed donor that coupling collapsed P(shares > 0 | property_wealth = 0)
+    to 0.011 against 0.055 observed; the production child seeds recover 0.039
+    (hold-out receipt re-run with exactly this derivation). The declared stage
+    seed stays the root and the children are deterministic.
+    """
+
+    return tuple(
+        int(child.generate_state(1, dtype=np.uint32)[0])
+        for child in np.random.SeedSequence(int(seed)).spawn(int(segments))
+    )
 
 
 def impute_was_wealth(
@@ -392,11 +424,16 @@ def impute_was_wealth(
     donor_encoded, recipient_encoded, encoded_predictors = encode_qrf_predictor_pair(
         donor, recipient_predictor_frame
     )
-    model = RegimeGatedQRF(n_estimators=n_estimators, seed=seed)
+    segment_seeds = was_wealth_segment_seeds(seed)
+    segment_models = iter(
+        RegimeGatedQRF(n_estimators=n_estimators, seed=segment_seed)
+        for segment_seed in segment_seeds
+    )
     raw = pd.DataFrame(index=recipient_encoded.index)
     fit_records: list[FitWeightRecord] = []
 
     def run_segment(base_predictors: Sequence[str], targets: Sequence[str]) -> None:
+        model = next(segment_models)
         state = model.start_chain(
             donor_encoded,
             list(base_predictors),
@@ -428,18 +465,37 @@ def run_segment(base_predictors: Sequence[str], targets: Sequence[str]) -> None:
     base = encoded_predictors
     run_segment(base, ("owned_land", "property_wealth"))
     donor_encoded["corporate_wealth"] = donor_encoded["corporate_wealth"].astype(float)
+    donor_encoded["private_pension_wealth"] = donor_encoded[
+        "private_pension_wealth"
+    ].astype(float)
     recipient_encoded["owned_land"] = raw["owned_land"]
     recipient_encoded["property_wealth"] = raw["property_wealth"]
+    # Private pension wealth is drawn first in the position the old folded
+    # corporate_wealth (84.7% pension by donor mass) occupied; the share-like
+    # components condition on it, and the fold into corporate_wealth follows.
     run_segment(
         (*base, "owned_land", "property_wealth"),
-        ("corporate_wealth_excl_isa", "stocks_and_shares_isa"),
+        (
+            "private_pension_wealth",
+            "corporate_wealth_excl_isa",
+            "stocks_and_shares_isa",
+        ),
     )
     raw["corporate_wealth"] = (
         raw["corporate_wealth_excl_isa"] + raw["stocks_and_shares_isa"]
     )
+    recipient_encoded["private_pension_wealth"] = raw["private_pension_wealth"]
     recipient_encoded["corporate_wealth"] = raw["corporate_wealth"]
+    # Downstream targets condition on both components, carrying the
+    # information the old folded corporate_wealth supplied as one column.
     run_segment(
-        (*base, "owned_land", "property_wealth", "corporate_wealth"),
+        (
+            *base,
+            "owned_land",
+            "property_wealth",
+            "private_pension_wealth",
+            "corporate_wealth",
+        ),
         (
             "gross_financial_wealth",
             "net_financial_wealth",
@@ -455,6 +511,7 @@ def run_segment(base_predictors: Sequence[str], targets: Sequence[str]) -> None:
     return UKWASWealthImputationResult(
         draws=raw.loc[:, UK_WAS_WEALTH_OUTPUT_COLUMNS],
         fit_weight_records=tuple(fit_records),
+        segment_seeds=segment_seeds,
     )
 
 
diff --git a/packages/microcosm-build/tests/test_spec_engine_country_bundles.py b/packages/microcosm-build/tests/test_spec_engine_country_bundles.py
index 9d028071f2..0adfa3083c 100644
--- a/packages/microcosm-build/tests/test_spec_engine_country_bundles.py
+++ b/packages/microcosm-build/tests/test_spec_engine_country_bundles.py
@@ -42,7 +42,7 @@
         ),
         (
             "uk",
-            "4793baa59a90930956faf8f5b422ece57da3445c7ed0030622ef62ff35dfb142",
+            "276fddeb17857f64fa1bbaae6551e52580c4ef352f3aba4da0eabd14ef13a668",
             {
                 "benunit.benunit_id",
                 "household.household_id",
diff --git a/packages/microcosm-build/tests/test_uk_was_wealth.py b/packages/microcosm-build/tests/test_uk_was_wealth.py
index 872ae69f30..d1c29df9ca 100644
--- a/packages/microcosm-build/tests/test_uk_was_wealth.py
+++ b/packages/microcosm-build/tests/test_uk_was_wealth.py
@@ -152,8 +152,11 @@ def test_was_donor_cleaning_arithmetic_and_exact_case_insensitive_columns() -> N
 
     assert donor["stocks_and_shares_isa"].tolist() == [5.0, 6.0]
     assert donor["cash_isa"].tolist() == [7.0, 8.0]
-    assert donor["corporate_wealth_excl_isa"].tolist() == [73.0, 166.0]
-    assert donor["corporate_wealth"].tolist() == [78.0, 172.0]
+    # Private pension wealth (total pensions less current DB) is its own
+    # output; corporate_wealth keeps only the share-like holdings.
+    assert donor["private_pension_wealth"].tolist() == [60.0, 150.0]
+    assert donor["corporate_wealth_excl_isa"].tolist() == [13.0, 16.0]
+    assert donor["corporate_wealth"].tolist() == [18.0, 22.0]
     assert donor["student_loan_balance"].tolist() == [5000.0, 2000.0]
     assert donor["region"].tolist() == ["LONDON", "SCOTLAND"]
     assert donor["is_renting"].tolist() == [True, False]
@@ -394,11 +397,12 @@ def test_was_imputer_uses_checkpointed_chain_segments(
     import microcosm.fit
 
     calls = []
+    seeds = []
 
     class FakeQRF:
         def __init__(self, *, n_estimators, seed):
             assert n_estimators == 7
-            assert seed == 0
+            seeds.append(seed)
 
         def start_chain(self, donor, predictors, targets, *, weights):
             assert weights == "weight"
@@ -437,11 +441,66 @@ def fit_draw_next(
 
     assert result.draws.columns.tolist() == list(UK_WAS_WEALTH_OUTPUT_COLUMNS)
     assert calls[0][1] == ("owned_land", "property_wealth")
-    assert calls[1][1] == ("corporate_wealth_excl_isa", "stocks_and_shares_isa")
+    assert calls[1][1] == (
+        "private_pension_wealth",
+        "corporate_wealth_excl_isa",
+        "stocks_and_shares_isa",
+    )
+    assert "private_pension_wealth" in calls[2][0]
     assert "corporate_wealth" in calls[2][0]
+    assert "private_pension_wealth" not in calls[1][0]
     assert calls[2][1][-1] == "cash_isa"
     fitted_targets = [name for _, targets in calls for name in targets]
     assert [record.fit_name for record in result.fit_weight_records] == [
         f"uk_was_2018_20_wealth:{target}" for target in fitted_targets
     ]
     assert {record.weight_kind for record in result.fit_weight_records} == {"explicit"}
+    # One independent RNG root per segment, derived from the declared seed.
+    assert seeds == list(module.was_wealth_segment_seeds(0))
+    assert len(set(seeds)) == 3
+    assert result.segment_seeds == tuple(seeds)
+
+
+def test_private_pension_wealth_split_preserves_the_old_corporate_wealth_identity() -> (
+    None
+):
+    """The pension component plus the new corporate_wealth reproduces the
+    pre-split corporate_wealth row for row, and the pension component is
+    exactly total pensions less current defined-benefit wealth."""
+    raw = _raw_was()
+    donor = clean_was_household_table(raw)
+
+    old_corporate_wealth = (
+        raw["totalpenr8_aggr"]
+        - raw["dvvaldbt_scaper8_aggr"]
+        + raw["DVFESHARESR8_aggr"]
+        + raw["DVFShUKVR8_aggr"]
+        + raw["DVFCollVR8_aggr"]
+        + raw["DVIISAVR8_aggR"]
+    )
+    assert (
+        donor["corporate_wealth"] + donor["private_pension_wealth"]
+    ).tolist() == old_corporate_wealth.tolist()
+    assert "private_pension_wealth" in UK_WAS_WEALTH_OUTPUT_COLUMNS
+    assert (
+        UK_WAS_WEALTH_OUTPUT_COLUMNS.index("private_pension_wealth")
+        == UK_WAS_WEALTH_OUTPUT_COLUMNS.index("corporate_wealth") + 1
+    )
+
+
+def test_segment_seeds_are_distinct_and_deterministic() -> None:
+    """Each chain segment starts its own fit/draw streams (start_chain respawns
+    from the model seed on every call), so the roots must differ and derive
+    deterministically from the declared stage seed."""
+    import microcosm.build.uk_runtime.was_wealth as module
+
+    seeds = module.was_wealth_segment_seeds(0)
+
+    # Golden pin: the production roots for the declared stage seed 0. Moving
+    # them is a spec-visible RNG change, never an accident.
+    assert seeds == (3757552657, 673228719, 3241444873)
+    assert len(seeds) == 3
+    assert len(set(seeds)) == 3
+    assert seeds == module.was_wealth_segment_seeds(0)
+    assert seeds != module.was_wealth_segment_seeds(1)
+    assert all(isinstance(seed, int) for seed in seeds)
diff --git a/packages/microcosm-data/src/microcosm/data/contract.py b/packages/microcosm-data/src/microcosm/data/contract.py
index c423461c50..4d765a463f 100644
--- a/packages/microcosm-data/src/microcosm/data/contract.py
+++ b/packages/microcosm-data/src/microcosm/data/contract.py
@@ -375,13 +375,13 @@
 # fingerprint derives from the manifest digest. Editing the spec moves all
 # three here in the same reviewed change.
 _UK_GATE_BATTERY_POLICY_SHA256 = (
-    "5459347c9077b2acd5970a62d818e3ddd063d86d6c3dbce4d32dcacec3bdc414"
+    "955d56d8a6ce608615b863a51c5040bdf3b5db16afb92cf1035979c6f55719b8"
 )
 _UK_GATE_BATTERY_GATES_MANIFEST_SHA256 = (
-    "f68e10d8ff6654b7fc707da0508ea063b0f3c96b8a813b7098298727d43b9d6d"
+    "7a8b261a2a9dd87e3a57579c55469d769deaa0002f6ee006370629ab0af8b4e0"
 )
 _UK_GATE_BATTERY_SPEC_FINGERPRINT = (
-    "2a4a8b18d024f80782b375539c87d57006592d64470553a4da5a378791254faa"
+    "e4c4a8fc302f79379e2e2ae75962428781c6cb3c0c31c825fd698240bfe6c89e"
 )
 #: Spec entry id -> the legacy gate name whose observable detail checks
 #: apply unchanged (the battery re-keys the report by entry id; the gate
@@ -607,10 +607,10 @@
     },
     "release_cut": {
         "gates_manifest_sha256": (
-            "18f07f40eead198a4436de7a43d4c0b13b9f2a9335bc84d4ab6b6a2ed75e597e"
+            "2c698843042584af8976196f92b2baf097beca93b846fca74671a1cc3cc879aa"
         ),
         "policy_sha256": (
-            "b2a6446da0ffc53c0a894618795d918163368a266ef01a2a3609587085162115"
+            "e73dcbcaa07e34d23c8cf40b251f19fd00d9d2b85202647ca0ea13cb1021769a"
         ),
     },
 }
diff --git a/packages/microcosm-data/tests/test_contract.py b/packages/microcosm-data/tests/test_contract.py
index 4f4910ebbb..27a4579119 100644
--- a/packages/microcosm-data/tests/test_contract.py
+++ b/packages/microcosm-data/tests/test_contract.py
@@ -135,13 +135,13 @@ def _trusted_terminal_gate_signing_key(monkeypatch) -> None:
 UK_GATE_BATTERY_PRODUCER = "microcosm.build.gate_battery"
 UK_GATE_BATTERY_SIGNING_KEY_ENV = "MICROCOSM_UK_TERMINAL_GATE_SIGNING_KEY"
 UK_GATE_BATTERY_POLICY_SHA256 = (
-    "5459347c9077b2acd5970a62d818e3ddd063d86d6c3dbce4d32dcacec3bdc414"
+    "955d56d8a6ce608615b863a51c5040bdf3b5db16afb92cf1035979c6f55719b8"
 )
 UK_GATE_BATTERY_GATES_MANIFEST_SHA256 = (
-    "f68e10d8ff6654b7fc707da0508ea063b0f3c96b8a813b7098298727d43b9d6d"
+    "7a8b261a2a9dd87e3a57579c55469d769deaa0002f6ee006370629ab0af8b4e0"
 )
 UK_GATE_BATTERY_SPEC_FINGERPRINT = (
-    "2a4a8b18d024f80782b375539c87d57006592d64470553a4da5a378791254faa"
+    "e4c4a8fc302f79379e2e2ae75962428781c6cb3c0c31c825fd698240bfe6c89e"
 )
 UK_GATE_BATTERY_DEGENERATE_EVIDENCE_SHA256 = (
     "d0d024043132fa07c378c393dbe2b24fe99bf19e876bcc39997d2c80cc9bd4f6"