Use exact FY2017 SNAP poverty-guideline income standards

changelog.d/history-snap-fpg-2017.fixed.md

@@ -0,0 +1 @@
+Corrected SNAP gross and net income standards for October 2016 through September 2017 using HHS's published household-size table.

policyengine_us/tests/policy/baseline/gov/usda/snap/eligibility/meets_snap_gross_income_test.yaml

@@ -310,3 +310,65 @@
           2026: GU
   output:
     meets_snap_gross_income_test: true
+
+# USDA FY 2017 Income Eligibility Standards, PDF pages 1-2.
+# https://fns-prod.azureedge.us/sites/default/files/resource-files/FY17-Income-Eligibility-Standards.pdf
+# Effective October 1, 2016 through September 30, 2017; ordinary gross/net
+# tables and separately rounded additional-person increments. HHS raw rows:
+# https://www.govinfo.gov/content/pkg/FR-2016-01-25/pdf/2016-01450.pdf#page=1
+# The actual-wage case checks only the ordinary gross predicate, not final SNAP.
+- name: Case 19, FY 2017 published gross standards are inclusive in all guideline geographies
+    and above size eight.
+  period: 2017-01
+  input:
+    snap_unit_size: [1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 12, 12, 1, 1, 2,
+      2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 12, 12, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6,
+      6, 7, 7, 8, 8, 9, 9, 12, 12]
+    state_group_str:
+      2017: [CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US,
+        CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US,
+        CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US,
+        CONTIGUOUS_US, CONTIGUOUS_US, AK, AK, AK, AK, AK, AK, AK, AK, AK, AK, AK, AK, AK,
+        AK, AK, AK, AK, AK, AK, AK, HI, HI, HI, HI, HI, HI, HI, HI, HI, HI, HI, HI, HI, HI,
+        HI, HI, HI, HI, HI, HI]
+    snap_gross_test_income: [1287, 1288, 1736, 1737, 2184, 2185, 2633, 2634, 3081, 3082, 3530,
+      3531, 3980, 3981, 4430, 4431, 4881, 4882, 6234, 6235, 1608, 1609, 2169, 2170, 2730,
+      2731, 3292, 3293, 3853, 3854, 4414, 4415, 4975, 4976, 5538, 5539, 6102, 6103, 7794,
+      7795, 1481, 1482, 1997, 1998, 2513, 2514, 3028, 3029, 3544, 3545, 4060, 4061, 4575,
+      4576, 5093, 5094, 5611, 5612, 7165, 7166]
+    has_snap_elderly_disabled_member: [false, false, false, false, false, false, false, false,
+      false, false, false, false, false, false, false, false, false, false, false, false,
+      false, false, false, false, false, false, false, false, false, false, false, false,
+      false, false, false, false, false, false, false, false, false, false, false, false,
+      false, false, false, false, false, false, false, false, false, false, false, false,
+      false, false, false, false]
+  output:
+    meets_snap_gross_income_test: [true, false, true, false, true, false, true, false, true,
+      false, true, false, true, false, true, false, true, false, true, false, true, false,
+      true, false, true, false, true, false, true, false, true, false, true, false, true,
+      false, true, false, true, false, true, false, true, false, true, false, true, false,
+      true, false, true, false, true, false, true, false, true, false, true, false]
+- name: Case 20, January 2017 wages one dollar above the three-person gross standard fail
+    the ordinary test.
+  period: 2017-01
+  input:
+    people:
+      person1:
+        age: {2017: 35}
+        employment_income: {2017: 26220}
+        weekly_hours_worked_before_lsr: {2017: 40}
+      person2:
+        age: {2017: 8}
+        is_tax_unit_dependent: {2017: true}
+      person3:
+        age: {2017: 4}
+        is_tax_unit_dependent: {2017: true}
+    spm_units:
+      spm_unit:
+        members: [person1, person2, person3]
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: {2017: TX}
+  output: {snap_unit_size: 3, snap_gross_test_income: 2185, has_snap_elderly_disabled_member: false,
+    meets_snap_gross_income_test: false}

policyengine_us/tests/policy/baseline/gov/usda/snap/eligibility/meets_snap_net_income_test.yaml

@@ -354,3 +354,34 @@
           2026: VI
   output:
     meets_snap_net_income_test: true
+
+# USDA FY 2017 Income Eligibility Standards, PDF pages 1-2.
+# https://fns-prod.azureedge.us/sites/default/files/resource-files/FY17-Income-Eligibility-Standards.pdf
+# Effective October 1, 2016 through September 30, 2017; ordinary gross/net
+# tables and separately rounded additional-person increments. HHS raw rows:
+# https://www.govinfo.gov/content/pkg/FR-2016-01-25/pdf/2016-01450.pdf#page=1
+- name: Case 21, FY 2017 published net standards are inclusive in all guideline geographies
+    and above size eight.
+  period: 2017-01
+  input:
+    snap_unit_size: [1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 12, 12, 1, 1, 2,
+      2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 12, 12, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6,
+      6, 7, 7, 8, 8, 9, 9, 12, 12]
+    state_group_str:
+      2017: [CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US,
+        CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US,
+        CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US,
+        CONTIGUOUS_US, CONTIGUOUS_US, AK, AK, AK, AK, AK, AK, AK, AK, AK, AK, AK, AK, AK,
+        AK, AK, AK, AK, AK, AK, AK, HI, HI, HI, HI, HI, HI, HI, HI, HI, HI, HI, HI, HI, HI,
+        HI, HI, HI, HI, HI, HI]
+    snap_net_income: [990, 991, 1335, 1336, 1680, 1681, 2025, 2026, 2370, 2371, 2715, 2716,
+      3061, 3062, 3408, 3409, 3755, 3756, 4796, 4797, 1237, 1238, 1669, 1670, 2100, 2101,
+      2532, 2533, 2964, 2965, 3395, 3396, 3827, 3828, 4260, 4261, 4694, 4695, 5996, 5997,
+      1140, 1141, 1536, 1537, 1933, 1934, 2330, 2331, 2726, 2727, 3123, 3124, 3520, 3521,
+      3918, 3919, 4317, 4318, 5514, 5515]
+  output:
+    meets_snap_net_income_test: [true, false, true, false, true, false, true, false, true,
+      false, true, false, true, false, true, false, true, false, true, false, true, false,
+      true, false, true, false, true, false, true, false, true, false, true, false, true,
+      false, true, false, true, false, true, false, true, false, true, false, true, false,
+      true, false, true, false, true, false, true, false, true, false, true, false]

policyengine_us/tests/policy/baseline/gov/usda/snap/income/snap_fpg.yaml

@@ -60,3 +60,63 @@
   output:
     # ($15,960 + 2 x $5,680) / 12.
     snap_fpg: 2_276.67
+
+# USDA FY 2017 Income Eligibility Standards, PDF pages 1-2.
+# https://fns-prod.azureedge.us/sites/default/files/resource-files/FY17-Income-Eligibility-Standards.pdf
+# Effective October 1, 2016 through September 30, 2017; ordinary gross/net
+# tables and separately rounded additional-person increments. HHS raw rows:
+# https://www.govinfo.gov/content/pkg/FR-2016-01-25/pdf/2016-01450.pdf#page=1
+- name: Case 5, FY 2017 uses the published nonuniform HHS rows and preserves zero-size fallback.
+  period: 2017-01
+  absolute_error_margin: 0.01
+  input:
+    snap_unit_size: [1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 1, 2, 3,
+      4, 5, 6, 7, 8, 9, 12, 0, 0, 0]
+    state_group_str:
+      2017: [CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US,
+        CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, CONTIGUOUS_US, AK, AK, AK, AK, AK, AK,
+        AK, AK, AK, AK, HI, HI, HI, HI, HI, HI, HI, HI, HI, HI, CONTIGUOUS_US, AK, HI]
+  output:
+    snap_fpg: [990.0, 1335.0, 1680.0, 2025.0, 2370.0, 2715.0, 3060.8333333333335, 3407.5,
+      3754.1666666666665, 4794.166666666667, 1236.6666666666667, 1668.3333333333333, 2100.0,
+      2531.6666666666665, 2963.3333333333335, 3395.0, 3826.6666666666665, 4260.0, 4693.333333333333,
+      5993.333333333333, 1139.1666666666667, 1535.8333333333333, 1932.5, 2329.1666666666665,
+      2725.8333333333335, 3122.5, 3519.1666666666665, 3917.5, 4315.833333333333, 5510.833333333333,
+      643.3333333333334, 803.3333333333334, 740.8333333333334]
+- name: Case 6, FY 2016 compatibility before the table window.
+  period: 2016-09
+  absolute_error_margin: 0.01
+  input:
+    snap_unit_size: 3
+    state_group_str: {2016: CONTIGUOUS_US}
+  output: {snap_fpg: 1674.1666666666667}
+- name: Case 7, FY 2017 begins in October 2016.
+  period: 2016-10
+  absolute_error_margin: 0.01
+  input:
+    snap_unit_size: 3
+    state_group_str: {2016: CONTIGUOUS_US}
+  output: {snap_fpg: 1680.0}
+- name: Case 8, FY 2017 retains the 2016 table through September.
+  period: 2017-09
+  absolute_error_margin: 0.01
+  input:
+    snap_unit_size: 3
+    state_group_str: {2017: CONTIGUOUS_US}
+  output: {snap_fpg: 1680.0}
+- name: Case 9, FY 2018 compatibility resumes the 2017 linear guideline.
+  period: 2017-10
+  absolute_error_margin: 0.01
+  input:
+    snap_unit_size: 3
+    state_group_str: {2017: CONTIGUOUS_US}
+  output: {snap_fpg: 1701.6666666666667}
+- name: Case 10, Guam and Virgin Islands use the FY 2017 contiguous guideline.
+  period: 2016-10
+  absolute_error_margin: 0.01
+  input:
+    snap_unit_size: [3, 3]
+    state_group_str:
+      2016: [GU, VI]
+  output:
+    snap_fpg: [1680, 1680]

policyengine_us/variables/gov/usda/snap/income/snap_fpg.py

@@ -1,5 +1,7 @@
 from policyengine_us.model_api import *
+from policyengine_us.variables.gov.hhs.tax_unit_fpg import fpg
 from policyengine_us.variables.gov.usda.snap.income.snap_income_standard_helpers import (
+    _snap_fpg_context,
     snap_monthly_fpg_amounts,
 )
 
@@ -14,9 +16,28 @@ class snap_fpg(Variable):
     reference = (
         "https://www.law.cornell.edu/cfr/text/7/273.9#a_3",
         "https://www.law.cornell.edu/uscode/text/7/2014#c",
+        # PDF pages 1-2.
+        "https://fns-prod.azureedge.us/sites/default/files/resource-files/FY17-Income-Eligibility-Standards.pdf#page=1",
     )
 
     def formula(spm_unit, period, parameters):
         n = spm_unit("snap_unit_size", period)
         p1, pn = snap_monthly_fpg_amounts(spm_unit, period, parameters)
-        return p1 + pn * (n - 1)
+        linear_monthly_fpg = p1 + pn * (n - 1)
+        state_group, guideline_date = _snap_fpg_context(spm_unit, period)
+        table = parameters(guideline_date).gov.hhs.fpg_table
+        if not table.in_effect:
+            return linear_monthly_fpg
+
+        use_table = (
+            np.isin(state_group, list(table.amount))
+            & np.isfinite(n)
+            & (n >= table.min_household_size)
+            & (n == np.floor(n))
+        )
+        # Keep the original monthly arithmetic outside HHS's source domain.
+        return where(
+            use_table,
+            fpg(n, state_group, guideline_date, parameters) / MONTHS_IN_YEAR,
+            linear_monthly_fpg,
+        )

policyengine_us/variables/gov/usda/snap/income/snap_income_standard_helpers.py

@@ -5,16 +5,8 @@
 SNAP_CONTIGUOUS_US_GUIDELINE_AREAS = ["GU", "VI"]
 
 
-def snap_monthly_fpg_amounts(spm_unit, period, parameters):
-    """Monthly poverty guideline for the first person and for each additional
-    person, from the guidelines SNAP adopts each October 1 (7 CFR 273.9(a)(3)).
-
-    Guam and the Virgin Islands use the guidelines for the 48 contiguous
-    States and the District of Columbia (7 CFR 273.9(a)(1)(i) and (a)(2)(i)),
-    so they read the contiguous-US guideline rather than their own zero
-    placeholders. This mapping is specific to SNAP income standards; the
-    households keep their own state group elsewhere.
-    """
+def _snap_fpg_context(spm_unit, period):
+    """Return SNAP's guideline area and October reference date."""
     state_group = spm_unit.household("state_group_str", period.this_year)
     state_group = np.where(
         np.isin(state_group, SNAP_CONTIGUOUS_US_GUIDELINE_AREAS),
@@ -27,6 +19,20 @@ def snap_monthly_fpg_amounts(spm_unit, period, parameters):
         instant_str = f"{year}-10-01"
     else:
         instant_str = f"{year - 1}-10-01"
+    return state_group, instant_str
+
+
+def snap_monthly_fpg_amounts(spm_unit, period, parameters):
+    """Monthly poverty guideline for the first person and for each additional
+    person, from the guidelines SNAP adopts each October 1 (7 CFR 273.9(a)(3)).
+
+    Guam and the Virgin Islands use the guidelines for the 48 contiguous
+    States and the District of Columbia (7 CFR 273.9(a)(1)(i) and (a)(2)(i)),
+    so they read the contiguous-US guideline rather than their own zero
+    placeholders. This mapping is specific to SNAP income standards; the
+    households keep their own state group elsewhere.
+    """
+    state_group, instant_str = _snap_fpg_context(spm_unit, period)
     p_fpg = parameters(instant_str).gov.hhs.fpg
     first_person = p_fpg.first_person[state_group] / MONTHS_IN_YEAR
     additional_person = p_fpg.additional_person[state_group] / MONTHS_IN_YEAR