diff --git a/changelog.d/fix-ca-mn-casualty-loss.fixed.md b/changelog.d/fix-ca-mn-casualty-loss.fixed.md
new file mode 100644
index 00000000000..50af78741a3
--- /dev/null
+++ b/changelog.d/fix-ca-mn-casualty-loss.fixed.md
@@ -0,0 +1 @@
+Allow non-disaster personal casualty and theft losses in California and Minnesota itemized deductions (and Minnesota alternative minimum taxable income), which do not follow the federal limit to declared disasters (Cal. Rev. & Tax. Code 17204(b); Minn. Stat. 290.0122, subd. 8): add `ca_casualty_loss_deduction` and `mn_casualty_loss_deduction`, each the loss less $100 and 10% of federal adjusted gross income, in place of the federal deduction.
diff --git a/policyengine_us/parameters/gov/irs/deductions/itemized/casualty/per_casualty_reduction.yaml b/policyengine_us/parameters/gov/irs/deductions/itemized/casualty/per_casualty_reduction.yaml
new file mode 100644
index 00000000000..b56d5b69462
--- /dev/null
+++ b/policyengine_us/parameters/gov/irs/deductions/itemized/casualty/per_casualty_reduction.yaml
@@ -0,0 +1,20 @@
+description: The IRS reduces each casualty or theft loss of personal-use property by this amount before applying the income floor.
+values:
+  2008-01-01: 100
+  2009-01-01: 500
+  2010-01-01: 100
+metadata:
+  unit: currency-USD
+  period: year
+  label: Casualty loss reduction per casualty
+  reference:
+    - title: 26 U.S.C. § 165(h)(1)
+      href: https://www.law.cornell.edu/uscode/text/26/165#h_1
+    - title: 2008 Form 4684, line 11
+      href: https://www.irs.gov/pub/irs-prior/f4684--2008.pdf#page=1
+    - title: 2009 Form 4684, line 11
+      href: https://www.irs.gov/pub/irs-prior/f4684--2009.pdf#page=1
+    - title: 2022 Form 4684, line 11
+      href: https://www.irs.gov/pub/irs-prior/f4684--2022.pdf#page=1
+    - title: IRS Publication 547 (2022), $100 Rule
+      href: https://www.irs.gov/pub/irs-prior/p547--2022.pdf#page=10
diff --git a/policyengine_us/parameters/gov/states/ca/tax/income/deductions/itemized/limit/excluded_deductions.yaml b/policyengine_us/parameters/gov/states/ca/tax/income/deductions/itemized/limit/excluded_deductions.yaml
index d3d5fd934b8..f0fc3bc9320 100644
--- a/policyengine_us/parameters/gov/states/ca/tax/income/deductions/itemized/limit/excluded_deductions.yaml
+++ b/policyengine_us/parameters/gov/states/ca/tax/income/deductions/itemized/limit/excluded_deductions.yaml
@@ -2,7 +2,9 @@ description: Itemized deductions excluded from CA high-AGI limitation.
 values:
   2021-01-01:
     - medical_expense_deduction
-    - casualty_loss_deduction
+    # California's own casualty and theft loss (Schedule CA line 15), which
+    # replaces the federal one in the pre-limitation total.
+    - ca_casualty_loss_deduction
     - non_mortgage_interest
 
 metadata:
@@ -18,5 +20,12 @@ metadata:
     href: https://www.ftb.ca.gov/forms/2024/2024-540-ca-instructions.html
   - title: 2025 Form 540 Schedule CA instructions
     href: https://www.ftb.ca.gov/forms/2025/2025-540-ca-instructions.html
+  - title: 2024 Schedule CA (540) instructions, line 29 itemized deductions worksheet, line 2
+    href: https://www.ftb.ca.gov/forms/2024/2024-540-booklet.pdf#page=68
   - title: Cal. Rev. & Tax. Code § 17077
     href: https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=RTC&sectionNum=17077
+  # R&TC 17077 adopts 26 U.S.C. 68, whose subsection (c)(3) (before P.L. 119-21)
+  # leaves casualty and theft losses described in 165(c)(2) or (3) out of the
+  # deductions the limitation reduces.
+  - title: 26 U.S.C. § 68 (amendment notes for subsection (c)(3))
+    href: https://www.law.cornell.edu/uscode/text/26/68
diff --git a/policyengine_us/reforms/states/mn/walz/mn_walz_hf1938.py b/policyengine_us/reforms/states/mn/walz/mn_walz_hf1938.py
index 78aed52cd19..0a2f4903d04 100644
--- a/policyengine_us/reforms/states/mn/walz/mn_walz_hf1938.py
+++ b/policyengine_us/reforms/states/mn/walz/mn_walz_hf1938.py
@@ -112,13 +112,22 @@ def formula(tax_unit, period, parameters):
             # ... calculate pre-limitation itemized deductions
             itm_deds_less_salt = tax_unit("itemized_deductions_less_salt", period)
             capped_property_taxes = tax_unit("capped_property_taxes", period)
-            mn_itm_deds = itm_deds_less_salt + capped_property_taxes
+            # Schedule M1SA line 19 takes Minnesota's own casualty and theft
+            # loss (Schedule M1CAT) in place of the federal one.
+            federal_casualty_loss = tax_unit("casualty_loss_deduction", period)
+            mn_casualty_loss = tax_unit("mn_casualty_loss_deduction", period)
+            mn_itm_deds = (
+                itm_deds_less_salt
+                - federal_casualty_loss
+                + mn_casualty_loss
+                + capped_property_taxes
+            )
             # ... calculate itemized deductions offset
             p = parameters(period).gov.states.mn.tax.income.deductions.itemized
             exempt_deds = add(
                 tax_unit,
                 period,
-                ["medical_expense_deduction", "casualty_loss_deduction"],
+                ["medical_expense_deduction", "mn_casualty_loss_deduction"],
             )
             net_deds = max_(0, mn_itm_deds - exempt_deds)
             net_deds_offset = p.reduction.alternate.rate * net_deds
diff --git a/policyengine_us/tests/policy/baseline/gov/states/ca/tax/income/deductions/itemized/ca_casualty_loss_deduction.yaml b/policyengine_us/tests/policy/baseline/gov/states/ca/tax/income/deductions/itemized/ca_casualty_loss_deduction.yaml
new file mode 100644
index 00000000000..ff9f57920e5
--- /dev/null
+++ b/policyengine_us/tests/policy/baseline/gov/states/ca/tax/income/deductions/itemized/ca_casualty_loss_deduction.yaml
@@ -0,0 +1,198 @@
+# 2024 Schedule CA (540) instructions, line 15 (Form 540 booklet, PDF p. 66):
+# federal law allows the personal casualty and theft loss deduction only for a
+# federally declared disaster; "California law does not conform." Filers
+# "complete another federal Form 4684 ... using California amounts".
+# Cal. Rev. & Tax. Code 17204(b) (as amended by SB 711, 2025): 26 U.S.C.
+# 165(h)(5) "shall not apply".
+# FTB Publication 1034 (PDF p. 4): "subtract $100 and then 10% of your federal
+# adjusted gross income."
+# 2024 Form 4684: line 11 enters $100; line 17 enters 10% of adjusted gross
+# income from Form 1040 line 11; line 18 is line 16 less line 17, not below 0.
+# A joint return is one individual for the $100 rule (165(h)(4)(B)). The model
+# records one loss amount per person, not separate casualty events, so a
+# return's losses are treated as one casualty. A dependent's loss belongs on
+# the dependent's own return, as the dependent's income does.
+
+- name: Case 1, the $100 reduction applies before the 10 percent floor.
+  period: 2024
+  input:
+    state_code: CA
+    employment_income: 100_000
+    casualty_loss: 15_000
+  output:
+    # Form 4684: line 12 = 15,000 - 100 = 14,900; line 17 = 10% x 100,000
+    # = 10,000; line 18 = 14,900 - 10,000.
+    ca_casualty_loss_deduction: 4_900
+    # California allows the loss though the federal deduction is suspended.
+    casualty_loss_deduction: 0
+
+- name: Case 2, a loss $100 above the floor nets to zero.
+  period: 2024
+  input:
+    state_code: CA
+    employment_income: 100_000
+    casualty_loss: 10_100
+  output:
+    # (10,100 - 100) - 10% x 100,000 = 10,000 - 10,000
+    ca_casualty_loss_deduction: 0
+
+- name: Case 3, a loss $101 above the floor leaves $1.
+  period: 2024
+  input:
+    state_code: CA
+    employment_income: 100_000
+    casualty_loss: 10_101
+  output:
+    # (10,101 - 100) - 10% x 100,000 = 10,001 - 10,000
+    ca_casualty_loss_deduction: 1
+
+- name: Case 4, a loss of exactly $100 is fully absorbed by the $100 reduction.
+  period: 2024
+  input:
+    state_code: CA
+    casualty_loss: 100
+  output:
+    ca_casualty_loss_deduction: 0
+
+- name: Case 5, with no income a loss is deductible above the $100.
+  period: 2024
+  input:
+    state_code: CA
+    casualty_loss: 101
+  output:
+    # (101 - 100) - 10% x 0
+    ca_casualty_loss_deduction: 1
+
+- name: Case 6, Publication 547 Example 1 with $80,000 of AGI.
+  period: 2024
+  input:
+    state_code: CA
+    employment_income: 80_000
+    casualty_loss: 14_800
+  output:
+    # IRS Publication 547 (2017, PDF p. 10), Example 1: loss after
+    # reimbursement 14,800; subtract $100 = 14,700; subtract 10% of 80,000 AGI
+    # = 6,700.
+    ca_casualty_loss_deduction: 6_700
+
+- name: Case 7, the floor uses federal AGI, not California AGI.
+  period: 2024
+  input:
+    state_code: CA
+    adjusted_gross_income: 100_000
+    ca_agi: 60_000
+    casualty_loss: 15_000
+  output:
+    # (15,000 - 100) - 10% x 100,000 federal AGI = 4,900. On California AGI it
+    # would be 14,900 - 6,000 = 8,900.
+    ca_casualty_loss_deduction: 4_900
+
+- name: Case 8, a negative federal AGI gives no floor, not a larger loss.
+  period: 2024
+  input:
+    state_code: CA
+    adjusted_gross_income: -20_000
+    casualty_loss: 15_000
+  output:
+    # The 10% floor is not allowed below zero: 15,000 - 100.
+    ca_casualty_loss_deduction: 14_900
+
+- name: Case 9, a joint return reduces the spouses' pooled losses by $100 once.
+  period: 2024
+  input:
+    people:
+      person1:
+        age: 40
+        employment_income: 60_000
+        casualty_loss: 10_000
+      person2:
+        age: 40
+        employment_income: 40_000
+        casualty_loss: 5_000
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+    households:
+      household:
+        members: [person1, person2]
+        state_code: CA
+  output:
+    filing_status: JOINT
+    # (10,000 + 5,000 - 100) - 10% x 100,000 = 14,900 - 10,000
+    ca_casualty_loss_deduction: 4_900
+
+- name: Case 10, a dependent's loss is left to the dependent's own return.
+  period: 2024
+  input:
+    people:
+      person1:
+        age: 40
+        employment_income: 100_000
+        casualty_loss: 15_000
+      person2:
+        age: 10
+        casualty_loss: 5_000
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+    households:
+      household:
+        members: [person1, person2]
+        state_code: CA
+  output:
+    is_tax_unit_dependent: [false, true]
+    # The child's 5,000 is not the parent's loss.
+    # (15,000 - 100) - 10% x 100,000 = 14,900 - 10,000
+    ca_casualty_loss_deduction: 4_900
+
+- name: Case 11, a loss only the dependent had gives the parent nothing.
+  period: 2024
+  input:
+    people:
+      person1:
+        age: 40
+        employment_income: 100_000
+      person2:
+        age: 10
+        casualty_loss: 15_000
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+    households:
+      household:
+        members: [person1, person2]
+        state_code: CA
+  output:
+    is_tax_unit_dependent: [false, true]
+    ca_casualty_loss_deduction: 0
+
+- name: Case 12, California keeps allowing the loss under its 2025 conformity date.
+  period: 2026
+  input:
+    state_code: CA
+    employment_income: 100_000
+    casualty_loss: 15_000
+  output:
+    # R&TC 17204(b) turns 165(h)(5) off for taxable years from 2025.
+    ca_casualty_loss_deduction: 4_900
+    casualty_loss_deduction: 0
+
+- name: Case 13, the deduction is zero outside California.
+  period: 2024
+  input:
+    state_code: NY
+    employment_income: 100_000
+    casualty_loss: 15_000
+  output:
+    ca_casualty_loss_deduction: 0
+
+- name: Case 14, lifting the federal suspension does not change California's deduction.
+  period: 2024
+  input:
+    gov.irs.deductions.itemized.casualty.active: true
+    state_code: CA
+    employment_income: 100_000
+    casualty_loss: 15_000
+  output:
+    # California's deduction does not read the federal switch.
+    ca_casualty_loss_deduction: 4_900
diff --git a/policyengine_us/tests/policy/baseline/gov/states/ca/tax/income/deductions/itemized/ca_itemized_deductions.yaml b/policyengine_us/tests/policy/baseline/gov/states/ca/tax/income/deductions/itemized/ca_itemized_deductions.yaml
index 13ce42b7d1c..a6847243c65 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/ca/tax/income/deductions/itemized/ca_itemized_deductions.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/ca/tax/income/deductions/itemized/ca_itemized_deductions.yaml
@@ -51,3 +51,26 @@
     ca_itemized_deductions_pre_limitation: 10_000
   output:
     ca_itemized_deductions: 7_000  # charity subject to limitation
+
+# 2024 Schedule CA (540) instructions, line 29 worksheet (Form 540 booklet,
+# PDF p. 68): line 2 takes medical expenses, investment interest, casualty and
+# theft losses and gambling losses out before the 80%/6% limitation. Cal. Rev.
+# & Tax. Code 17077 adopts 26 U.S.C. 68, which leaves 165(c)(3) losses out.
+- name: California casualty loss is not subject to the high-AGI limitation
+  absolute_error_margin: 0.01
+  period: 2024
+  input:
+    state_code: CA
+    filing_status: SINGLE
+    adjusted_gross_income: 244_857 + 50_000
+    ca_charitable_deduction: 1_000
+    casualty_loss: 40_000
+  output:
+    # Form 4684: (40,000 - 100) - 10% x 294,857 = 39,900 - 29,485.70
+    ca_casualty_loss_deduction: 10_414.30
+    ca_itemized_deductions_pre_limitation: 11_414.30
+    # Worksheet: line 3 = 11,414.30 - 10,414.30 = 1,000; line 4 = 80% x 1,000
+    # = 800; line 8 = 6% x 50,000 = 3,000; line 9 = 800.
+    # 11,414.30 - 800. Were the loss limited too, line 4 would be 9,131.44,
+    # line 9 would be 3,000 and the result 8,414.30.
+    ca_itemized_deductions: 10_614.30
diff --git a/policyengine_us/tests/policy/baseline/gov/states/ca/tax/income/deductions/itemized/ca_itemized_deductions_pre_limitation.yaml b/policyengine_us/tests/policy/baseline/gov/states/ca/tax/income/deductions/itemized/ca_itemized_deductions_pre_limitation.yaml
index 524500a4c91..eb522ef4498 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/ca/tax/income/deductions/itemized/ca_itemized_deductions_pre_limitation.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/ca/tax/income/deductions/itemized/ca_itemized_deductions_pre_limitation.yaml
@@ -385,3 +385,31 @@
     # Also includes #10032's IRA 219(g) phase-out, since this is a two-cause
     # CA + IRA cell.
     state_income_tax_before_refundable_credits: 4441.45
+
+# 2024 Schedule CA (540) instructions, line 15 (Form 540 booklet, PDF p. 66):
+# "California law does not conform" to the federal limit of personal casualty
+# losses to declared disasters; filers complete a second Form 4684 with
+# California amounts.
+- name: California allows a non-disaster casualty loss the federal return does not.
+  period: 2024
+  input:
+    state_code: CA
+    employment_income: 100_000
+    casualty_loss: 15_000
+  output:
+    casualty_loss_deduction: 0
+    # Form 4684: (15,000 - 100) - 10% x 100,000 = 4,900
+    ca_itemized_deductions_pre_limitation: 4_900
+
+- name: California counts the casualty loss once when the federal suspension is lifted.
+  period: 2024
+  input:
+    gov.irs.deductions.itemized.casualty.active: true
+    state_code: CA
+    employment_income: 100_000
+    casualty_loss: 15_000
+  output:
+    ca_casualty_loss_deduction: 4_900
+    # The federal deduction, now positive, is replaced by California's 4,900,
+    # not added to it.
+    ca_itemized_deductions_pre_limitation: 4_900
diff --git a/policyengine_us/tests/policy/baseline/gov/states/mn/tax/income/mn_amt_taxable_income.yaml b/policyengine_us/tests/policy/baseline/gov/states/mn/tax/income/mn_amt_taxable_income.yaml
index 3a65303cfad..4310e3a2c90 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/mn/tax/income/mn_amt_taxable_income.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/mn/tax/income/mn_amt_taxable_income.yaml
@@ -19,3 +19,29 @@
     state_code: MN
   output:
     mn_amt_taxable_income: 200_000 - 250 - 3_000
+
+# 2024 Schedule M1MT, line 12 (PDF p. 1): "Casualty and theft losses (from line
+# 19 of Schedule M1SA)", Minnesota's own amount from Schedule M1CAT.
+- name: MN AMT taxable income subtracts the Minnesota casualty loss
+  period: 2024
+  input:
+    adjusted_gross_income: 200_000
+    mn_itemizing: true
+    casualty_loss: 40_000
+    state_code: MN
+  output:
+    # The federal deduction is suspended.
+    casualty_loss_deduction: 0
+    # M1CAT: (40,000 - 100) - 10% x 200,000 = 19,900
+    mn_casualty_loss_deduction: 19_900
+    mn_amt_taxable_income: 200_000 - 19_900
+
+- name: MN AMT taxable income leaves the casualty loss out for a non-itemizer
+  period: 2024
+  input:
+    adjusted_gross_income: 200_000
+    mn_itemizing: false
+    casualty_loss: 40_000
+    state_code: MN
+  output:
+    mn_amt_taxable_income: 200_000
diff --git a/policyengine_us/tests/policy/baseline/gov/states/mn/tax/income/mn_casualty_loss_deduction.yaml b/policyengine_us/tests/policy/baseline/gov/states/mn/tax/income/mn_casualty_loss_deduction.yaml
new file mode 100644
index 00000000000..a051c1798fa
--- /dev/null
+++ b/policyengine_us/tests/policy/baseline/gov/states/mn/tax/income/mn_casualty_loss_deduction.yaml
@@ -0,0 +1,181 @@
+# Minn. Stat. 290.0122, subd. 8: losses under 26 U.S.C. 165(c)(3), "including
+# the provisions of section 165(h) ... but disregarding paragraph (h)(5)".
+# 2024 Schedule M1SA instructions, line 19 (PDF p. 7): a loss is deductible
+# only to the extent each loss "is more than $100" and the year's losses
+# "reduced by $100" are "more than 10% of the amount on line 1 of Form M1".
+# 2024 Schedule M1CAT (PDF p. 1): line 11 "Enter $100"; line 18 "Enter the
+# amount from line 1 of Form M1" (federal adjusted gross income); line 19
+# "Multiply line 18 by 10%"; line 20 subtracts line 19 from line 17, not below
+# 0, and goes to M1SA line 19. The 2018 M1CAT has the same $100 reduction and
+# 10% floor; its line 20 goes to M1SA line 18, and its line 18 takes Schedule
+# M1NC line 38 (federal adjustments) from filers of that schedule, which the
+# model does not have. These cases are ordinary losses:
+# the 2020 Schedule M1SA's net qualified disaster loss (federal Form 4684 line
+# 15, $500 and no 10% floor) is not modeled.
+# A joint return is one individual for the $100 rule (165(h)(4)(B)). The model
+# records one loss amount per person, not separate casualty events, so a
+# return's losses are treated as one casualty. A dependent's loss belongs on
+# the dependent's own return, as the dependent's income does.
+
+- name: Case 1, the $100 reduction applies before the 10 percent floor.
+  period: 2024
+  input:
+    state_code: MN
+    employment_income: 100_000
+    casualty_loss: 15_000
+  output:
+    # M1CAT: line 12 = 15,000 - 100 = 14,900; line 19 = 10% x 100,000
+    # = 10,000; line 20 = 14,900 - 10,000.
+    mn_casualty_loss_deduction: 4_900
+    # Minnesota allows the loss though the federal deduction is suspended.
+    casualty_loss_deduction: 0
+
+- name: Case 2, a loss $100 above the floor nets to zero.
+  period: 2024
+  input:
+    state_code: MN
+    employment_income: 100_000
+    casualty_loss: 10_100
+  output:
+    # (10,100 - 100) - 10% x 100,000 = 10,000 - 10,000
+    mn_casualty_loss_deduction: 0
+
+- name: Case 3, a loss $101 above the floor leaves $1.
+  period: 2024
+  input:
+    state_code: MN
+    employment_income: 100_000
+    casualty_loss: 10_101
+  output:
+    # (10,101 - 100) - 10% x 100,000 = 10,001 - 10,000
+    mn_casualty_loss_deduction: 1
+
+- name: Case 4, a loss of exactly $100 is fully absorbed by the $100 reduction.
+  period: 2024
+  input:
+    state_code: MN
+    casualty_loss: 100
+  output:
+    mn_casualty_loss_deduction: 0
+
+- name: Case 5, Publication 547 Example 1 with $80,000 of AGI.
+  period: 2024
+  input:
+    state_code: MN
+    employment_income: 80_000
+    casualty_loss: 14_800
+  output:
+    # IRS Publication 547 (2017, PDF p. 10), Example 1: 14,800 - 100 = 14,700;
+    # less 10% of 80,000 = 6,700.
+    mn_casualty_loss_deduction: 6_700
+
+- name: Case 6, a negative federal AGI gives no floor, not a larger loss.
+  period: 2024
+  input:
+    state_code: MN
+    adjusted_gross_income: -20_000
+    casualty_loss: 15_000
+  output:
+    # M1CAT line 18 has no "enter 0" rule; the floor is held at zero so the
+    # deduction never exceeds the reduced loss: 15,000 - 100.
+    mn_casualty_loss_deduction: 14_900
+
+- name: Case 7, a joint return reduces the spouses' pooled losses by $100 once.
+  period: 2024
+  input:
+    people:
+      person1:
+        age: 40
+        employment_income: 60_000
+        casualty_loss: 10_000
+      person2:
+        age: 40
+        employment_income: 40_000
+        casualty_loss: 5_000
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+    households:
+      household:
+        members: [person1, person2]
+        state_code: MN
+  output:
+    filing_status: JOINT
+    # (10,000 + 5,000 - 100) - 10% x 100,000 = 14,900 - 10,000
+    mn_casualty_loss_deduction: 4_900
+
+- name: Case 8, a dependent's loss is left to the dependent's own return.
+  period: 2024
+  input:
+    people:
+      person1:
+        age: 40
+        employment_income: 100_000
+        casualty_loss: 15_000
+      person2:
+        age: 10
+        casualty_loss: 5_000
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+    households:
+      household:
+        members: [person1, person2]
+        state_code: MN
+  output:
+    is_tax_unit_dependent: [false, true]
+    # (15,000 - 100) - 10% x 100,000 = 14,900 - 10,000
+    mn_casualty_loss_deduction: 4_900
+
+- name: Case 9, a loss only the dependent had gives the parent nothing.
+  period: 2024
+  input:
+    people:
+      person1:
+        age: 40
+        employment_income: 100_000
+      person2:
+        age: 10
+        casualty_loss: 15_000
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+    households:
+      household:
+        members: [person1, person2]
+        state_code: MN
+  output:
+    is_tax_unit_dependent: [false, true]
+    mn_casualty_loss_deduction: 0
+
+- name: Case 10, the 2018 Schedule M1CAT already allows a non-disaster loss.
+  period: 2018
+  input:
+    state_code: MN
+    employment_income: 50_000
+    casualty_loss: 8_000
+  output:
+    # For a filer with no Schedule M1NC: (8,000 - 100) - 10% x 50,000
+    # = 7,900 - 5,000
+    mn_casualty_loss_deduction: 2_900
+    casualty_loss_deduction: 0
+
+- name: Case 11, the deduction is zero outside Minnesota.
+  period: 2024
+  input:
+    state_code: WI
+    employment_income: 100_000
+    casualty_loss: 15_000
+  output:
+    mn_casualty_loss_deduction: 0
+
+- name: Case 12, lifting the federal suspension does not change Minnesota's deduction.
+  period: 2024
+  input:
+    gov.irs.deductions.itemized.casualty.active: true
+    state_code: MN
+    employment_income: 100_000
+    casualty_loss: 15_000
+  output:
+    # Minnesota's deduction does not read the federal switch.
+    mn_casualty_loss_deduction: 4_900
diff --git a/policyengine_us/tests/policy/baseline/gov/states/mn/tax/income/mn_itemized_deductions.yaml b/policyengine_us/tests/policy/baseline/gov/states/mn/tax/income/mn_itemized_deductions.yaml
index 632dba542f1..acb1fa03b73 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/mn/tax/income/mn_itemized_deductions.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/mn/tax/income/mn_itemized_deductions.yaml
@@ -39,7 +39,9 @@
     adjusted_gross_income: 1_206_050
     interest_deduction: 10_000
     medical_expense_deduction: 400
-    casualty_loss_deduction: 200
+    # Minnesota's own casualty loss (Schedule M1SA line 19) is exempt from the
+    # reduction, as medical expenses are.
+    mn_casualty_loss_deduction: 200
     state_code: MN
   output:
     mn_itemized_deductions: (10_000 + 400 + 200) - 0.80 * 10_000
@@ -90,3 +92,60 @@
     state_code: MN
   output:
     mn_itemized_deductions: 10_000
+
+# Schedule M1SA line 19 takes the casualty and theft loss from Schedule M1CAT:
+# each casualty less $100, then less 10% of Form M1 line 1 (federal AGI). Minn.
+# Stat. 290.0122, subd. 8, disregards the federal limit to declared disasters.
+- name: 2024 MN itemized deductions include a non-disaster casualty loss
+  absolute_error_margin: 0.01
+  period: 2024
+  input:
+    filing_status: SINGLE
+    adjusted_gross_income: 100_000
+    interest_deduction: 10_000
+    casualty_loss: 15_000
+    state_code: MN
+  output:
+    # The federal deduction is suspended.
+    casualty_loss_deduction: 0
+    # M1CAT: (15,000 - 100) - 10% x 100,000 = 4,900
+    mn_casualty_loss_deduction: 4_900
+    # M1SA line 25: 10,000 interest + 4,900 casualty; AGI is under the
+    # $232,500 reduction threshold.
+    mn_itemized_deductions: 14_900
+
+# M1SA line 26 Worksheet B, step 2, takes lines 4, 13 and 19 out before the
+# 80% reduction (Minn. Stat. 290.0122, subd. 2(d)(3)).
+- name: 2024 MN casualty loss is exempt from the high-income reduction
+  absolute_error_margin: 0.01
+  period: 2024
+  input:
+    filing_status: SINGLE
+    adjusted_gross_income: 2_000_000
+    interest_deduction: 10_000
+    casualty_loss: 250_000
+    state_code: MN
+  output:
+    # M1CAT: (250,000 - 100) - 10% x 2,000,000 = 49,900
+    mn_casualty_loss_deduction: 49_900
+    # AGI is over $1,053,750, so the reduction is 80% of the deductions
+    # other than the casualty loss: 0.8 x 10,000 = 8,000.
+    # 10,000 + 49,900 - 8,000. Were the loss reduced too, the result would be
+    # 59,900 - 0.8 x 59,900 = 11,980.
+    mn_itemized_deductions: 51_900
+
+- name: 2024 MN counts the casualty loss once when the federal suspension is lifted
+  absolute_error_margin: 0.01
+  period: 2024
+  input:
+    gov.irs.deductions.itemized.casualty.active: true
+    filing_status: SINGLE
+    adjusted_gross_income: 100_000
+    interest_deduction: 10_000
+    casualty_loss: 15_000
+    state_code: MN
+  output:
+    mn_casualty_loss_deduction: 4_900
+    # The federal deduction, now positive inside itemized_deductions_less_salt,
+    # is replaced by Minnesota's 4,900, not added to it.
+    mn_itemized_deductions: 14_900
diff --git a/policyengine_us/tests/policy/contrib/states/mn/walz/mn_walz_hf1938.yaml b/policyengine_us/tests/policy/contrib/states/mn/walz/mn_walz_hf1938.yaml
index ba403f7eda6..aacb657d111 100644
--- a/policyengine_us/tests/policy/contrib/states/mn/walz/mn_walz_hf1938.yaml
+++ b/policyengine_us/tests/policy/contrib/states/mn/walz/mn_walz_hf1938.yaml
@@ -109,3 +109,22 @@
     state_code: MN
   output:
     mn_itemized_deductions: 10_000
+
+- name: Itemized deductions with reform take the Minnesota casualty loss and exempt it from the offset
+  absolute_error_margin: 0.5
+  period: 2023
+  reforms: policyengine_us.reforms.states.mn.walz.mn_walz_hf1938.mn_walz_hf1938
+  input:
+    gov.contrib.states.mn.walz.hf1938.repeal: true
+    filing_status: SINGLE
+    adjusted_gross_income: 2_000_000
+    interest_deduction: 10_000
+    casualty_loss: 250_000
+    state_code: MN
+  output:
+    # Schedule M1CAT: (250,000 - 100) - 10% x 2,000,000 = 49,900
+    mn_casualty_loss_deduction: 49_900
+    # Offset: the lesser of 80% of the deductions other than the casualty loss
+    # (0.8 x 10,000 = 8,000) and 3% of AGI over $220,650 (53,380.50).
+    # 10,000 + 49,900 - 8,000
+    mn_itemized_deductions: 51_900
diff --git a/policyengine_us/tests/unit/test_ca_mn_casualty_loss_deduction_properties.py b/policyengine_us/tests/unit/test_ca_mn_casualty_loss_deduction_properties.py
new file mode 100644
index 00000000000..96193c6eb9b
--- /dev/null
+++ b/policyengine_us/tests/unit/test_ca_mn_casualty_loss_deduction_properties.py
@@ -0,0 +1,211 @@
+"""Properties of California's and Minnesota's casualty loss deductions.
+
+Both states allow a personal casualty or theft loss under 26 U.S.C. 165(h)
+without the federal limit to declared disasters (Cal. Rev. & Tax. Code
+17204(b), Schedule CA (540) line 15; Minn. Stat. 290.0122, subd. 8, Schedule
+M1CAT). Each reduces the loss by $100 (Form 4684 line 11; M1CAT line 11) and
+allows the rest above 10% of federal adjusted gross income (Form 4684 line 17
+and FTB Publication 1034; M1CAT lines 18-19). A joint return is one individual
+for the $100 rule, and a dependent's loss belongs on the dependent's own
+return. The model records one loss amount per person and no event count, so a
+return's losses are treated as one casualty.
+
+`ca_casualty_loss_deduction` and `mn_casualty_loss_deduction` are two copies
+of that computation for an ordinary loss. The model has no disaster input and
+no Minnesota Schedule M1NC, so the properties below do not cover the 2020
+Schedule M1SA's net qualified disaster loss or the 2018 M1CAT's Schedule M1NC
+line 38 base. Hypothesis draws batches of tax units (single or joint,
+with up to two dependents who have their own losses), places each in
+California and in Minnesota, and runs each batch as one vectorized baseline
+simulation. For every tax unit and year:
+
+1. Each copy equals a closed-form reference on the head's and spouse's losses:
+   max(max(loss - 100, 0) - 10% x max(AGI, 0), 0). Dependents' losses never
+   enter it, and neither does California AGI.
+2. Bounds: 0 <= deduction <= max(loss - 100, 0).
+3. Each copy is zero outside its state.
+4. Differential: the two copies agree on the same drawn units.
+5. The federal `casualty_loss_deduction` is zero in these years, so neither
+   state follows the federal suspension.
+
+A deterministic grid adds the boundary inputs ($0, $99, $100, $101, the floor
+plus $100) and checks monotonicity: each copy rises with the loss and falls
+with AGI, and is zero for a loss of $100 or less.
+"""
+
+import itertools
+
+import numpy as np
+import pytest
+from hypothesis import HealthCheck, given, settings
+from hypothesis import strategies as st
+
+from policyengine_us import Simulation
+
+REDUCTION = 100  # Form 4684 line 11; Schedule M1CAT line 11
+FLOOR = 0.1  # Form 4684 line 17; Schedule M1CAT line 19
+TOLERANCE = 0.01
+CA_AGI_OFFSET = 7_000  # makes California AGI differ from federal AGI
+# 2018 is the first year of the federal suspension; 2026 follows California's
+# move to a January 1, 2025 conformity date.
+YEARS = [2018, 2026]
+STATE_OF = {
+    "ca_casualty_loss_deduction": "CA",
+    "mn_casualty_loss_deduction": "MN",
+}
+STATES = list(STATE_OF.values())
+
+
+def reference(loss, agi):
+    reduced = np.maximum(loss - REDUCTION, 0)
+    return np.maximum(reduced - FLOOR * np.maximum(agi, 0), 0)
+
+
+def every_year(value):
+    return {year: value for year in YEARS}
+
+
+def build_situation(units):
+    """Place each unit in each state, with the same federal AGI."""
+    people, tax_units, households = {}, {}, {}
+    rows = []  # (filer loss, AGI, state) for each tax unit, in order
+    for state in STATES:
+        for i, unit in enumerate(units):
+            name = f"{state}{i}"
+            members = [f"{name}_head"]
+            people[members[0]] = {
+                "age": every_year(40),
+                "casualty_loss": every_year(unit["head_loss"]),
+            }
+            filer_loss = unit["head_loss"]
+            if unit["joint"]:
+                members.append(f"{name}_spouse")
+                people[members[-1]] = {
+                    "age": every_year(40),
+                    "casualty_loss": every_year(unit["spouse_loss"]),
+                }
+                filer_loss += unit["spouse_loss"]
+            for d, dependent_loss in enumerate(unit["dependent_losses"]):
+                members.append(f"{name}_dep{d}")
+                people[members[-1]] = {
+                    "age": every_year(10),
+                    "is_tax_unit_dependent": every_year(True),
+                    "casualty_loss": every_year(dependent_loss),
+                }
+            agi = unit["agi"]
+            tax_units[name] = {
+                "members": members,
+                "adjusted_gross_income": every_year(agi),
+                # California's floor is on federal AGI (FTB Publication 1034),
+                # so a different California AGI must not move its copy.
+                "ca_agi": every_year(agi + CA_AGI_OFFSET),
+            }
+            households[name] = {"members": members, "state_code": every_year(state)}
+            rows.append((filer_loss, agi, state))
+    situation = {"people": people, "tax_units": tax_units, "households": households}
+    loss, agi, state = (np.array(column) for column in zip(*rows))
+    return situation, loss.astype(float), agi.astype(float), state
+
+
+def check_reference_and_bounds(sim, loss, agi, state):
+    for variable, own_state in STATE_OF.items():
+        for year in YEARS:
+            value = sim.calculate(variable, year)
+            expected = np.where(state == own_state, reference(loss, agi), 0)
+            np.testing.assert_allclose(
+                value, expected, atol=TOLERANCE, err_msg=f"{variable} {year}"
+            )
+            assert np.all(value >= 0)
+            assert np.all(value <= np.maximum(loss - REDUCTION, 0) + TOLERANCE)
+
+
+def check_copies_agree(sim, state):
+    for year in YEARS:
+        california = sim.calculate("ca_casualty_loss_deduction", year)
+        minnesota = sim.calculate("mn_casualty_loss_deduction", year)
+        # The same drawn units, in the same order, sit in each state.
+        np.testing.assert_allclose(
+            california[state == "CA"], minnesota[state == "MN"], atol=TOLERANCE
+        )
+        # Neither state follows the federal suspension.
+        assert np.all(sim.calculate("casualty_loss_deduction", year) == 0)
+
+
+money = st.one_of(
+    st.sampled_from([0, 50, 99, 100, 101, 150]),
+    st.integers(0, 60_000),
+).map(float)
+agis = st.one_of(
+    st.sampled_from([0, 1_000, 50_000]),
+    st.integers(-20_000, 300_000),
+).map(float)
+tax_unit_strategy = st.fixed_dictionaries(
+    {
+        "joint": st.booleans(),
+        "head_loss": money,
+        "spouse_loss": money,
+        "dependent_losses": st.lists(money, max_size=2),
+        "agi": agis,
+    }
+)
+SETTINGS = dict(
+    max_examples=20,
+    deadline=None,
+    derandomize=True,
+    suppress_health_check=[HealthCheck.too_slow, HealthCheck.data_too_large],
+)
+
+
+@settings(**SETTINGS)
+@given(st.lists(tax_unit_strategy, min_size=4, max_size=15))
+def test_copies_match_the_form_4684_reference(units):
+    situation, loss, agi, state = build_situation(units)
+    sim = Simulation(situation=situation)
+    check_reference_and_bounds(sim, loss, agi, state)
+    check_copies_agree(sim, state)
+
+
+GRID_LOSSES = [0, 50, 99, 100, 101, 150, 5_000, 10_100, 10_101, 30_000]
+GRID_AGIS = [-10_000, 0, 1_000, 50_000, 100_000, 300_000]
+GRID_DEPENDENT_LOSSES = [0, 20_000]
+
+
+def grid_situation():
+    units = [
+        {
+            "joint": False,
+            "head_loss": float(loss),
+            "spouse_loss": 0.0,
+            "dependent_losses": [float(dependent_loss)],
+            "agi": float(agi),
+        }
+        for loss, agi, dependent_loss in itertools.product(
+            GRID_LOSSES, GRID_AGIS, GRID_DEPENDENT_LOSSES
+        )
+    ]
+    return build_situation(units)
+
+
+@pytest.fixture(scope="module")
+def grid():
+    situation, loss, agi, state = grid_situation()
+    return Simulation(situation=situation), loss, agi, state
+
+
+@pytest.mark.parametrize("variable, year", list(itertools.product(STATE_OF, YEARS)))
+def test_grid_monotone_and_boundaries(grid, variable, year):
+    sim, loss, agi, state = grid
+    rows = state == STATE_OF[variable]
+    value = sim.calculate(variable, year)[rows]
+    np.testing.assert_allclose(value, reference(loss[rows], agi[rows]), atol=TOLERANCE)
+    shape = (len(GRID_LOSSES), len(GRID_AGIS), len(GRID_DEPENDENT_LOSSES))
+    table = value.reshape(shape)
+    # A dependent's loss never changes the filer's deduction.
+    np.testing.assert_allclose(table[..., 0], table[..., 1], atol=TOLERANCE)
+    assert np.all(np.diff(table, axis=0) >= -TOLERANCE), "falls as the loss rises"
+    assert np.all(np.diff(table, axis=1) <= TOLERANCE), "rises as AGI rises"
+    # A loss of $100 or less is absorbed by the $100 reduction.
+    small = np.array(GRID_LOSSES) <= REDUCTION
+    assert np.all(table[small] == 0)
+    # Guard against a vacuous pass.
+    assert table.max() > 0
diff --git a/policyengine_us/variables/gov/states/ca/tax/income/deductions/itemized/ca_casualty_loss_deduction.py b/policyengine_us/variables/gov/states/ca/tax/income/deductions/itemized/ca_casualty_loss_deduction.py
new file mode 100644
index 00000000000..1e4ef8389cb
--- /dev/null
+++ b/policyengine_us/variables/gov/states/ca/tax/income/deductions/itemized/ca_casualty_loss_deduction.py
@@ -0,0 +1,56 @@
+from policyengine_us.model_api import *
+
+
+class ca_casualty_loss_deduction(Variable):
+    value_type = float
+    entity = TaxUnit
+    label = "California casualty loss deduction"
+    unit = USD
+    definition_period = YEAR
+    reference = (
+        # Cal. Rev. & Tax. Code § 17201: the IRC itemized deductions,
+        # including 26 U.S.C. 165, apply
+        "https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=RTC&sectionNum=17201",
+        # Cal. Rev. & Tax. Code § 17204(b): 26 U.S.C. 165(h)(5) shall not apply
+        "https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=RTC&sectionNum=17204",
+        # 2024 Schedule CA (540) instructions, line 15
+        "https://www.ftb.ca.gov/forms/2024/2024-540-booklet.pdf#page=66",
+        # 2025 Schedule CA (540) instructions, line 15
+        "https://www.ftb.ca.gov/forms/2025/2025-540-ca-instructions.html",
+        # FTB Publication 1034, How to Calculate a Disaster Loss - Individuals
+        # (2025 edition; the 2024 edition has the same text on the same page)
+        "https://www.ftb.ca.gov/forms/misc/1034.pdf#page=4",
+        "https://web.archive.org/web/20250529011540/https://www.ftb.ca.gov/forms/misc/1034.pdf#page=4",
+        # 2024 Form 4684, lines 10-18
+        "https://www.irs.gov/pub/irs-prior/f4684--2024.pdf#page=1",
+    )
+    defined_for = StateCode.CA
+    documentation = """
+    California adopts 26 U.S.C. 165 (R&TC 17201) but not the federal limit of
+    personal casualty losses to declared disasters (R&TC 17204(b)). Schedule CA
+    (540) line 15 has filers complete a second federal Form 4684 with California
+    amounts, so a non-disaster personal casualty or theft loss stays
+    deductible: each casualty is reduced by $100, and the rest is deductible
+    above 10% of federal adjusted gross income.
+    """
+
+    def formula(tax_unit, period, parameters):
+        p = parameters(period).gov.irs.deductions.itemized.casualty
+        # California never applies the federal suspension: its IRC conformity
+        # date was January 1, 2015 through 2024, before 26 U.S.C. 165(h)(5)
+        # was enacted, and R&TC 17204(b) turns (h)(5) off from 2025.
+        # Only the owner of the property claims the loss. A dependent's loss
+        # belongs on the dependent's own return, as the dependent's income
+        # does: adjusted gross income leaves it out.
+        loss = tax_unit_non_dep_add(tax_unit, period, ["casualty_loss"])
+        # Form 4684 line 11 reduces each casualty by $100. California states no
+        # amount of its own; it takes 165(h)(1) through R&TC 17201. A joint
+        # return is one individual for the $100 rule. The model records one
+        # loss amount per person, not separate casualty events, so the
+        # return's losses are treated as one casualty and the reduction
+        # applies once.
+        reduced_loss = max_(loss - p.per_casualty_reduction, 0)
+        # Form 4684 line 17 and FTB Publication 1034: 10% of federal adjusted
+        # gross income (Form 540 line 13), not California AGI.
+        positive_agi = tax_unit("positive_agi", period)
+        return max_(reduced_loss - positive_agi * p.floor, 0)
diff --git a/policyengine_us/variables/gov/states/ca/tax/income/deductions/itemized/ca_itemized_deductions_pre_limitation.py b/policyengine_us/variables/gov/states/ca/tax/income/deductions/itemized/ca_itemized_deductions_pre_limitation.py
index 80c39a22960..091b5150824 100644
--- a/policyengine_us/variables/gov/states/ca/tax/income/deductions/itemized/ca_itemized_deductions_pre_limitation.py
+++ b/policyengine_us/variables/gov/states/ca/tax/income/deductions/itemized/ca_itemized_deductions_pre_limitation.py
@@ -12,12 +12,17 @@ class ca_itemized_deductions_pre_limitation(Variable):
         "https://www.ftb.ca.gov/forms/2022/2022-540-ca-instructions.html",
         "https://www.ftb.ca.gov/forms/2025/2025-540-ca-instructions.html",
         "https://www.ftb.ca.gov/about-ftb/data-reports-plans/summary-of-federal-income-tax-changes/index.html",
+        # 2024 Schedule CA (540) instructions, line 15
+        "https://www.ftb.ca.gov/forms/2024/2024-540-booklet.pdf#page=66",
     )
     defined_for = StateCode.CA
 
     def formula(tax_unit, period, parameters):
         # Exclude the replaced federal amounts before summation, so changes
-        # to federal charity/misc rules cannot cause cancellation errors.
+        # to federal charity/misc/casualty rules cannot cause cancellation
+        # errors. Schedule CA line 15 replaces the federal casualty loss,
+        # which is limited to declared disasters from 2018, with California's
+        # own.
         federal_components = parameters(period).gov.irs.deductions.itemized_deductions
         deductions = [
             variable
@@ -28,6 +33,7 @@ def formula(tax_unit, period, parameters):
                 "charitable_deduction",
                 "charitable_deduction_for_non_itemizers",
                 "misc_deduction",
+                "casualty_loss_deduction",
             )
         ]
         deductions += [
@@ -35,6 +41,7 @@ def formula(tax_unit, period, parameters):
             "real_estate_taxes",
             "ca_charitable_deduction",
             "ca_misc_deduction",
+            "ca_casualty_loss_deduction",
         ]
         # Federal investment interest is nested in interest_deduction.
         return add(tax_unit, period, deductions) - add(
diff --git a/policyengine_us/variables/gov/states/mn/tax/income/amt/mn_amt_taxable_income.py b/policyengine_us/variables/gov/states/mn/tax/income/amt/mn_amt_taxable_income.py
index 50dc8cc7602..83736e79da5 100644
--- a/policyengine_us/variables/gov/states/mn/tax/income/amt/mn_amt_taxable_income.py
+++ b/policyengine_us/variables/gov/states/mn/tax/income/amt/mn_amt_taxable_income.py
@@ -10,6 +10,8 @@ class mn_amt_taxable_income(Variable):
     reference = (
         "https://www.revenue.state.mn.us/sites/default/files/2023-02/m1mt_21.pdf",
         "https://www.revenue.state.mn.us/sites/default/files/2023-01/m1mt_22.pdf",
+        # 2024 Schedule M1MT, line 12
+        "https://www.revenue.state.mn.us/sites/default/files/2025-07/m1mt-24.pdf#page=1",
     )
     defined_for = StateCode.MN
 
@@ -19,7 +21,9 @@ def formula(tax_unit, period, parameters):
         SOME_DEDUCTIONS = [
             "charitable_deduction",
             "medical_expense_deduction",
-            "casualty_loss_deduction",
+            # M1MT line 12 takes the casualty and theft loss from Schedule
+            # M1SA line 19, Minnesota's own amount.
+            "mn_casualty_loss_deduction",
         ]
         some_itm_deds = itemizing * add(tax_unit, period, SOME_DEDUCTIONS)
         AMT_SUBTRACTIONS = [
diff --git a/policyengine_us/variables/gov/states/mn/tax/income/deductions/mn_casualty_loss_deduction.py b/policyengine_us/variables/gov/states/mn/tax/income/deductions/mn_casualty_loss_deduction.py
new file mode 100644
index 00000000000..e8d3b9bfdf1
--- /dev/null
+++ b/policyengine_us/variables/gov/states/mn/tax/income/deductions/mn_casualty_loss_deduction.py
@@ -0,0 +1,62 @@
+from policyengine_us.model_api import *
+
+
+class mn_casualty_loss_deduction(Variable):
+    value_type = float
+    entity = TaxUnit
+    label = "Minnesota casualty loss deduction"
+    unit = USD
+    definition_period = YEAR
+    reference = (
+        # Minn. Stat. § 290.0122, subd. 8: losses under 26 U.S.C. 165(c)(3),
+        # including 165(h) but disregarding (h)(5)
+        "https://www.revisor.mn.gov/statutes/cite/290.0122#stat.290.0122.8",
+        # 2024 Schedule M1SA, line 19, and its instructions
+        # PDF pages 1, 7
+        "https://www.revenue.state.mn.us/sites/default/files/2024-12/m1sa-24.pdf#page=1",
+        # 2024 Schedule M1CAT, lines 10-20
+        "https://www.revenue.state.mn.us/sites/default/files/2024-12/m1cat-24.pdf#page=1",
+        # 2018 Schedule M1CAT, lines 10-20
+        "https://www.revenue.state.mn.us/sites/default/files/2018-11/m1cat_18.pdf#page=1",
+        # 2020 Schedule M1SA instructions, line 19, qualified disaster loss
+        # PDF pages 6-7
+        "https://www.revenue.state.mn.us/sites/default/files/2023-01/m1sa_20.pdf#page=6",
+    )
+    defined_for = StateCode.MN
+    documentation = """
+    Minnesota allows personal casualty and theft losses under 26 U.S.C. 165(h)
+    but disregards the federal limit to declared disasters (Minn. Stat.
+    290.0122, subd. 8). Schedule M1CAT reduces each casualty by $100 and allows
+    the rest above 10% of Form M1 line 1 (federal adjusted gross income); the
+    result goes on Schedule M1SA line 19. Two cases on the forms are not
+    modeled: for 2018, filers of Schedule M1NC (federal adjustments) use its
+    line 38 in place of Form M1 line 1; and the 2020 Schedule M1SA takes a
+    net qualified disaster loss from federal Form 4684 line 15 ($500 per
+    casualty, no 10% floor), which can be deducted without itemizing.
+    """
+
+    def formula(tax_unit, period, parameters):
+        p = parameters(period).gov.irs.deductions.itemized.casualty
+        # For 2018 Minnesota computed tax under the Internal Revenue Code as
+        # amended through December 16, 2016 (Minn. Stat. 290.993), before
+        # 26 U.S.C. 165(h)(5) existed, and Schedule M1CAT has applied the $100
+        # and 10% to an ordinary (not qualified disaster) loss in every year
+        # since, so the federal suspension never applies.
+        # Only the owner of the property claims the loss. A dependent's loss
+        # belongs on the dependent's own return, as the dependent's income
+        # does: adjusted gross income leaves it out.
+        loss = tax_unit_non_dep_add(tax_unit, period, ["casualty_loss"])
+        # M1CAT line 11: "Enter $100". A joint return is one individual for the
+        # $100 rule (165(h)(4)(B)). The model records one loss amount per
+        # person, not separate casualty events, so the return's losses are
+        # treated as one casualty and the reduction applies once.
+        reduced_loss = max_(loss - p.per_casualty_reduction, 0)
+        # M1CAT lines 18-20: subtract 10% of Form M1 line 1 (federal adjusted
+        # gross income). The 2018 form takes Schedule M1NC line 38 instead
+        # from filers of that schedule; the model has no Schedule M1NC, so
+        # 2018 also uses federal adjusted gross income. The form does not say
+        # to enter 0 for a negative AGI; like Form 4684 and the federal
+        # deduction, the floor is not allowed to go below zero, so the
+        # deduction never exceeds the reduced loss.
+        positive_agi = tax_unit("positive_agi", period)
+        return max_(reduced_loss - positive_agi * p.floor, 0)
diff --git a/policyengine_us/variables/gov/states/mn/tax/income/deductions/mn_itemized_deductions.py b/policyengine_us/variables/gov/states/mn/tax/income/deductions/mn_itemized_deductions.py
index bbd8191185d..7fc89edb407 100644
--- a/policyengine_us/variables/gov/states/mn/tax/income/deductions/mn_itemized_deductions.py
+++ b/policyengine_us/variables/gov/states/mn/tax/income/deductions/mn_itemized_deductions.py
@@ -12,6 +12,11 @@ class mn_itemized_deductions(Variable):
         "https://www.revenue.state.mn.us/sites/default/files/2023-12/m1_inst_21.pdf",
         "https://www.revenue.state.mn.us/sites/default/files/2023-12/m1_22.pdf",
         "https://www.revenue.state.mn.us/sites/default/files/2024-02/m1-inst-22.pdf",
+        # 2024 Schedule M1SA, line 19, and the line 26 limitation worksheets
+        # PDF pages 1, 8
+        "https://www.revenue.state.mn.us/sites/default/files/2024-12/m1sa-24.pdf#page=1",
+        # Minn. Stat. § 290.0122, subd. 2(d) and subd. 8
+        "https://www.revisor.mn.gov/statutes/cite/290.0122",
     )
     defined_for = StateCode.MN
 
@@ -24,13 +29,26 @@ def formula(tax_unit, period, parameters):
         # ... calculate pre-limitation itemized deductions
         itm_deds_less_salt = tax_unit("itemized_deductions_less_salt", period)
         capped_property_taxes = tax_unit("capped_property_taxes", period)
-        mn_itm_deds = itm_deds_less_salt + capped_property_taxes
+        # Schedule M1SA line 19 takes Minnesota's own casualty and theft loss
+        # (Schedule M1CAT) in place of the federal one, which is limited to
+        # declared disasters from 2018.
+        federal_casualty_loss = tax_unit("casualty_loss_deduction", period)
+        mn_casualty_loss = tax_unit("mn_casualty_loss_deduction", period)
+        mn_itm_deds = (
+            itm_deds_less_salt
+            - federal_casualty_loss
+            + mn_casualty_loss
+            + capped_property_taxes
+        )
         # ... calculate itemized deductions offset
         p = parameters(period).gov.states.mn.tax.income.deductions.itemized
+        # Minn. Stat. 290.0122, subd. 2(d), and the M1SA line 26 worksheets
+        # (step 2: lines 4, 13 and 19) leave medical expenses and casualty
+        # and theft losses out of the reduction.
         exempt_deds = add(
             tax_unit,
             period,
-            ["medical_expense_deduction", "casualty_loss_deduction"],
+            ["medical_expense_deduction", "mn_casualty_loss_deduction"],
         )
         net_deds = max_(0, mn_itm_deds - exempt_deds)
         filing_status = tax_unit("filing_status", period)