Correct eight Vermont renter credit income limits to HUD's limits

changelog.d/fix-vt-renter-credit-income-limits.fixed.md

@@ -0,0 +1 @@
+Correct eight Vermont renter credit income limits for 2021, 2023, 2024 and 2025 to HUD's limits and the department's tables, including Washington County's 2025 seven-person partial-credit limit ($88,990; the TY2025 booklet prints $88,880).

policyengine_us/parameters/gov/states/vt/tax/income/credits/renter/income_limit_ami/fifty_percent.yaml

@@ -1,7 +1,7 @@
 description: Vermont limits the partial renter credit to filers with income below this amount, based on the county and household size.
 metadata:
   propagate_metadata_to_children: true
-  unit: /1
+  unit: currency-USD
   period: year
   breakdown:
   - list(range(1,9))
@@ -10,8 +10,30 @@ metadata:
   label: Vermont partial renter credit income limit
   reference:
     # The table is derived from the official Vermont government website. The legal code refers to area median income.
+    # The published tables equal HUD's very low-income (l50) limit for 2021-2023 and
+    # 1.3 times it for 2024-2025, rounded to the nearest $10. For Franklin and Grand
+    # Isle they use the average across Vermont's twelve HUD income-limit areas, rounded
+    # to the nearest $10 before the multiplier (32 V.S.A. § 6061(20)).
   - title: 32 V.S.A. §6066. Homestead Property Tax Credit and Renter Credit (b)(B)
     href: https://law.justia.com/codes/vermont/2022/title-32/chapter-154/section-6066/
+  - title: 32 V.S.A. § 6061(20), very low-income limit
+    href: https://legislature.vermont.gov/statutes/section/32/154/06061
+  - title: 2025 Renter Credit Website Calculator, 2025 Income Limits sheet
+    href: https://tax.vermont.gov/sites/tax/files/documents/2025%20Renter%20Credit%20Website%20Calculator.xlsx
+  - title: 2024 Renter Credit Website Calculator, 2024 Income Limits sheet
+    href: https://tax.vermont.gov/sites/tax/files/documents/2024%20Renter%20Credit%20Website%20Calculator.xlsx
+  - title: 2023 Renter Credit Website Calculator, 2023 Income Limits sheet
+    href: https://web.archive.org/web/20250526044955/https://tax.vermont.gov/document/2023-renter-credit-website-calculator
+  - title: HUD FY2025 Section 8 income limits (l50 columns)
+    href: https://www.huduser.gov/portal/datasets/il/il25/Section8-FY25.xlsx
+  - title: HUD FY2024 Section 8 income limits (l50 columns)
+    href: https://www.huduser.gov/portal/datasets/il/il24/Section8-FY24.xlsx
+  - title: HUD FY2023 Section 8 income limits (l50 columns)
+    href: https://www.huduser.gov/portal/datasets/il/il23/Section8-FY23.xlsx
+  - title: HUD FY2022 Section 8 income limits (l50 columns)
+    href: https://www.huduser.gov/portal/datasets/il/il22/Section8-FY22.xlsx
+  - title: HUD FY2021 Section 8 income limits (l50 columns)
+    href: https://www.huduser.gov/portal/datasets/il/il21/Section8-FY21.xlsx
   - title: 2021 Vermont instruction booklet
     href: https://tax.vermont.gov/sites/tax/files/documents/Income-Booklet-2021.pdf#page=34
   - title: 2022 Vermont instruction booklet
@@ -187,7 +209,7 @@ metadata:
     2024-01-01: 49_400
     2025-01-01: 53_950
   WINDSOR_COUNTY_VT:
-    2021-01-01: 31_350
+    2021-01-01: 31_550
     2022-01-01: 35_250
     2023-01-01: 37_350
     2024-01-01: 52_260
@@ -263,7 +285,7 @@ metadata:
     2021-01-01: 37_000
     2022-01-01: 41_150
     2023-01-01: 43_600
-    2024-01-01: 61_960
+    2024-01-01: 61_690
     2025-01-01: 64_610
   WINDHAM_COUNTY_VT:
     2021-01-01: 35_250
@@ -566,7 +588,7 @@ metadata:
   FRANKLIN_COUNTY_VT:
     2021-01-01: 49_980
     2022-01-01: 55_100
-    2023-01-01: 56_250
+    2023-01-01: 58_320
     2024-01-01: 80_510
     2025-01-01: 87_390
   GRAND_ISLE_COUNTY_VT:
@@ -578,7 +600,7 @@ metadata:
   LAMOILLE_COUNTY_VT:
     2021-01-01: 48_550
     2022-01-01: 53_150
-    2023-01-01: 58_320
+    2023-01-01: 56_250
     2024-01-01: 76_570
     2025-01-01: 83_590
   ORANGE_COUNTY_VT:
@@ -604,7 +626,9 @@ metadata:
     2022-01-01: 56_700
     2023-01-01: 60_050
     2024-01-01: 84_960
-    2025-01-01: 88_880
+    # The TY2025 booklet prints $88,880. The 2025 calculator has $88,990, which is
+    # 1.3 times HUD's FY2025 limit of $68,450 ($88,985), rounded to the nearest $10.
+    2025-01-01: 88_990
   WINDHAM_COUNTY_VT:
     2021-01-01: 48_550
     2022-01-01: 53_150
@@ -640,7 +664,7 @@ metadata:
     2021-01-01: 63_300
     2022-01-01: 70_850
     2023-01-01: 75_000
-    2024-01-01: 102_850
+    2024-01-01: 102_050
     2025-01-01: 111_410
   ESSEX_COUNTY_VT:
     2021-01-01: 51_700

policyengine_us/parameters/gov/states/vt/tax/income/credits/renter/income_limit_ami/thirty_percent.yaml

@@ -10,12 +10,33 @@ metadata:
   label: Vermont full renter credit income limit
   reference:
     # The table is derived from the official Vermont government website. The legal code refers to area median income.
+    # The published tables equal HUD's extremely low-income (ELI) limit. For Franklin
+    # and Grand Isle they use the average across Vermont's twelve HUD income-limit
+    # areas, rounded to the nearest $10 (32 V.S.A. § 6061(19)).
   - title: 32 V.S.A. §6066. Homestead Property Tax Credit and Renter Credit (b)(B)
     href: https://law.justia.com/codes/vermont/2022/title-32/chapter-154/section-6066/
+  - title: 32 V.S.A. § 6061(19), extremely low-income limit
+    href: https://legislature.vermont.gov/statutes/section/32/154/06061
+  - title: 2025 Renter Credit Website Calculator, 2025 Income Limits sheet
+    href: https://tax.vermont.gov/sites/tax/files/documents/2025%20Renter%20Credit%20Website%20Calculator.xlsx
+  - title: 2024 Renter Credit Website Calculator, 2024 Income Limits sheet
+    href: https://tax.vermont.gov/sites/tax/files/documents/2024%20Renter%20Credit%20Website%20Calculator.xlsx
+  - title: 2023 Renter Credit Website Calculator, 2023 Income Limits sheet
+    href: https://web.archive.org/web/20250526044955/https://tax.vermont.gov/document/2023-renter-credit-website-calculator
+  - title: HUD FY2025 Section 8 income limits (ELI columns)
+    href: https://www.huduser.gov/portal/datasets/il/il25/Section8-FY25.xlsx
+  - title: HUD FY2024 Section 8 income limits (ELI columns)
+    href: https://www.huduser.gov/portal/datasets/il/il24/Section8-FY24.xlsx
+  - title: HUD FY2023 Section 8 income limits (ELI columns)
+    href: https://www.huduser.gov/portal/datasets/il/il23/Section8-FY23.xlsx
+  - title: HUD FY2022 Section 8 income limits (ELI columns)
+    href: https://www.huduser.gov/portal/datasets/il/il22/Section8-FY22.xlsx
+  - title: HUD FY2021 Section 8 income limits (ELI columns)
+    href: https://www.huduser.gov/portal/datasets/il/il21/Section8-FY21.xlsx
   - title: 2021 Vermont instruction booklet
     href: https://tax.vermont.gov/sites/tax/files/documents/Income-Booklet-2021.pdf#page=34
   - title: 2022 Vermont instruction booklet
-    href: https://tax.vermont.gov/sites/tax/files/documents/Income%20Booklet-2022.pdf#page=35
+    href: https://tax.vermont.gov/sites/tax/files/documents/Income%20Booklet-2022.pdf#page=36
   - title: Vt. 2023 Income Tax Return Booklet
     href: https://tax.vermont.gov/sites/tax/files/documents/Income-Booklet-2023.pdf#page=36
   - title: Vt. 2024 Income Tax Return Booklet
@@ -294,7 +315,7 @@ metadata:
     2021-01-01: 26_500
     2022-01-01: 27_750
     2023-01-01: 30_000
-    2024-01-01: 30_000
+    2024-01-01: 31_200
     2025-01-01: 32_150
   CHITTENDEN_COUNTY_VT:
     2021-01-01: 28_750
@@ -382,7 +403,7 @@ metadata:
     2024-01-01: 36_580
     2025-01-01: 37_650
   CHITTENDEN_COUNTY_VT:
-    2021-01-01: 31_040
+    2021-01-01: 31_050
     2022-01-01: 34_800
     2023-01-01: 36_850
     2024-01-01: 38_550
@@ -600,6 +621,8 @@ metadata:
     2024-01-01: 47_340
     2025-01-01: 48_650
   WASHINGTON_COUNTY_VT:
+    # The TY2021 booklet prints $41,120. HUD's FY2021 limit, and every other
+    # county's 7-person value in the booklet, is $40,120.
     2021-01-01: 40_120
     2022-01-01: 41_910
     2023-01-01: 45_420

policyengine_us/tests/policy/baseline/gov/states/vt/tax/income/credits/rent/test_vt_renter_credit_income_limits.py

@@ -0,0 +1,149 @@
+"""Check Vermont's renter credit income limit tables against HUD's limits.
+
+32 V.S.A. § 6061(19)-(20) define the full and partial credit limits from HUD's
+Section 8 income limits: the extremely low-income limit, and 1.3 times the very
+low-income limit. Franklin and Grand Isle use the state average instead. PE
+transcribes the department's published tables, and PE also bundles HUD's limits
+(gov/hud/income_limits) for FY2024 onward, so the two must agree for every year
+both cover. The department rounds to the nearest $10, half up; for Franklin and
+Grand Isle it averages across Vermont's twelve HUD areas and rounds that average
+to $10 before applying the multiplier. Transcription slips in the 2024 and 2025
+tables (including the TY2025 booklet's $88,880 for Washington County, seven
+people, where 1.3 x $68,450 gives $88,990) broke this check.
+"""
+
+from decimal import ROUND_HALF_UP, Decimal
+
+import pytest
+
+from policyengine_us.parameters.gov.hud.income_limits import income_limits
+from policyengine_us.system import system
+
+TABLES = system.parameters.gov.states.vt.tax.income.credits.renter.income_limit_ami
+SIZES = range(1, 9)
+VERY_LOW_INCOME_MULTIPLIER = Decimal("1.3")
+COUNTY_FIPS = {
+    "ADDISON_COUNTY_VT": "50001",
+    "BENNINGTON_COUNTY_VT": "50003",
+    "CALEDONIA_COUNTY_VT": "50005",
+    "CHITTENDEN_COUNTY_VT": "50007",
+    "ESSEX_COUNTY_VT": "50009",
+    "FRANKLIN_COUNTY_VT": "50011",
+    "GRAND_ISLE_COUNTY_VT": "50013",
+    "LAMOILLE_COUNTY_VT": "50015",
+    "ORANGE_COUNTY_VT": "50017",
+    "ORLEANS_COUNTY_VT": "50019",
+    "RUTLAND_COUNTY_VT": "50021",
+    "WASHINGTON_COUNTY_VT": "50023",
+    "WINDHAM_COUNTY_VT": "50025",
+    "WINDSOR_COUNTY_VT": "50027",
+}
+STATE_AVERAGE_COUNTIES = ("FRANKLIN_COUNTY_VT", "GRAND_ISLE_COUNTY_VT")
+
+
+def _table(name):
+    """Map (year, county, size) to each value dated January 1 in a table."""
+    values = {}
+    for size in SIZES:
+        for county, parameter in (
+            TABLES.children[name].children[str(size)].children.items()
+        ):
+            for entry in parameter.values_list:
+                year, month_day = int(entry.instant_str[:4]), entry.instant_str[5:]
+                assert month_day == "01-01", entry.instant_str
+                values[(year, county, size)] = entry.value
+    return values
+
+
+PARTIAL = _table("fifty_percent")
+FULL = _table("thirty_percent")
+TABLE_YEARS = sorted({year for year, _, _ in PARTIAL})
+HUD_YEARS = sorted(set(TABLE_YEARS) & set(income_limits["year"].unique().tolist()))
+
+
+def _round_to_ten(amount):
+    return int((Decimal(amount) / 10).quantize(Decimal(1), rounding=ROUND_HALF_UP) * 10)
+
+
+def _hud(year):
+    rows = income_limits[
+        (income_limits["year"] == year)
+        & income_limits["county_fips"].isin(COUNTY_FIPS.values())
+    ].set_index("county_fips")
+    assert len(rows) == len(COUNTY_FIPS)
+    return rows
+
+
+def _expected(year, county, size, column, multiplier):
+    rows = _hud(year)
+    if county in STATE_AVERAGE_COUNTIES:
+        # Franklin and Grand Isle share the Burlington-South Burlington HUD
+        # area with Chittenden, so the other twelve counties are the twelve
+        # distinct HUD areas.
+        for other in STATE_AVERAGE_COUNTIES:
+            assert rows.loc[COUNTY_FIPS[other]].equals(
+                rows.loc[COUNTY_FIPS["CHITTENDEN_COUNTY_VT"]]
+            )
+        areas = [COUNTY_FIPS[c] for c in COUNTY_FIPS if c not in STATE_AVERAGE_COUNTIES]
+        average = Decimal(int(rows.loc[areas, f"{column}_{size}"].sum())) / len(areas)
+        return _round_to_ten(_round_to_ten(average) * multiplier)
+    return _round_to_ten(
+        Decimal(int(rows.loc[COUNTY_FIPS[county], f"{column}_{size}"])) * multiplier
+    )
+
+
+def test_hud_comparison_covers_2024_onward():
+    # The published tables start in 2021; pe-us copies each parameter's first
+    # value back to 2015 (tools/parameters.py backdate_parameters).
+    assert set(range(2021, 2026)) <= set(TABLE_YEARS)
+    assert HUD_YEARS[:2] == [2024, 2025]
+
+
+@pytest.mark.parametrize("year", HUD_YEARS)
+@pytest.mark.parametrize("county", sorted(COUNTY_FIPS))
+@pytest.mark.parametrize("size", SIZES)
+def test_partial_credit_limit_is_1_3_times_hud_very_low_income_limit(
+    size, county, year
+):
+    assert PARTIAL[(year, county, size)] == _expected(
+        year, county, size, "very_low_income", VERY_LOW_INCOME_MULTIPLIER
+    )
+
+
+@pytest.mark.parametrize("year", HUD_YEARS)
+@pytest.mark.parametrize("county", sorted(COUNTY_FIPS))
+@pytest.mark.parametrize("size", SIZES)
+def test_full_credit_limit_is_hud_extremely_low_income_limit(size, county, year):
+    assert FULL[(year, county, size)] == _expected(
+        year, county, size, "extremely_low_income", Decimal(1)
+    )
+
+
+def test_tables_cover_every_county_size_and_year():
+    keys = {
+        (year, county, size)
+        for year in TABLE_YEARS
+        for county in COUNTY_FIPS
+        for size in SIZES
+    }
+    assert set(PARTIAL) == keys
+    assert set(FULL) == keys
+
+
+@pytest.mark.parametrize("year", TABLE_YEARS)
+@pytest.mark.parametrize("county", sorted(COUNTY_FIPS))
+def test_limits_rise_with_household_size_and_full_stays_below_partial(county, year):
+    partial = [PARTIAL[(year, county, size)] for size in SIZES]
+    full = [FULL[(year, county, size)] for size in SIZES]
+    assert partial == sorted(partial)
+    assert full == sorted(full)
+    assert all(f < p for f, p in zip(full, partial))
+    assert all(value % 10 == 0 for value in partial + full)
+
+
+@pytest.mark.parametrize("year", TABLE_YEARS)
+def test_franklin_and_grand_isle_share_the_state_average(year):
+    for table in (PARTIAL, FULL):
+        assert [table[(year, "FRANKLIN_COUNTY_VT", size)] for size in SIZES] == [
+            table[(year, "GRAND_ISLE_COUNTY_VT", size)] for size in SIZES
+        ]