[codex] Model Medicare Part B premiums net of MSP coverage

policyengine_us/parameters/gov/census/index.yaml

@@ -0,0 +1,4 @@
+metadata:
+  propagate_metadata_to_children: true
+  economy: false
+  household: false

policyengine_us/parameters/gov/census/spm/index.yaml

@@ -0,0 +1,4 @@
+metadata:
+  propagate_metadata_to_children: true
+  economy: false
+  household: false

policyengine_us/parameters/gov/census/spm/work_expense/index.yaml

@@ -0,0 +1,4 @@
+metadata:
+  propagate_metadata_to_children: true
+  economy: false
+  household: false

policyengine_us/parameters/gov/census/spm/work_expense/weekly_amount.yaml

@@ -0,0 +1,31 @@
+description: Weekly work-expense deduction amount used in Census Supplemental Poverty Measure calculations.
+values:
+  2009-01-01: 28.0500
+  2010-01-01: 25.5000
+  2011-01-01: 27.1575
+  2012-01-01: 33.0225
+  2013-01-01: 39.3975
+  2014-01-01: 39.2530
+  2015-01-01: 40.0945
+  2016-01-01: 38.4710
+  2017-01-01: 36.3460
+  2018-01-01: 37.1025
+  2019-01-01: 39.7205
+  2020-01-01: 39.6100
+  2021-01-01: 38.0630
+  2022-01-01: 31.0080
+  2023-01-01: 33.4050
+  2024-01-01: 34.9945
+
+metadata:
+  unit: currency-USD
+  period: year
+  uprating: gov.bls.cpi.cpi_u
+  label: Census SPM weekly work-expense deduction amount
+  reference:
+    - title: Supplemental Poverty Measure (SPM) Technical Documentation
+      href: https://www2.census.gov/programs-surveys/supplemental-poverty-measure/technical-documentation/spm_techdoc.pdf
+    - title: Poverty in the United States 2023
+      href: https://www2.census.gov/library/publications/2024/demo/p60-283.pdf
+    - title: Poverty in the United States 2024
+      href: https://www2.census.gov/library/publications/2025/demo/p60-287.pdf

policyengine_us/tests/policy/baseline/gov/hhs/medicare/eligibility/income_adjusted_part_b_premium.yaml

@@ -15,7 +15,7 @@
   period: 2025
   input:
     age: 65
-    filing_status: JOINT
+    tax_unit_married: true
     adjusted_gross_income:
       2023: 266_001  # IRMAA uses income from 2 years prior
     tax_exempt_interest_income:
@@ -54,7 +54,7 @@
   period: 2025
   input:
     age: 65
-    filing_status: JOINT
+    tax_unit_married: true
     adjusted_gross_income:
       2023: 200_000  # IRMAA uses income from 2 years prior
     tax_exempt_interest_income:
@@ -67,7 +67,7 @@
   period: 2025
   input:
     age: 65
-    filing_status: JOINT
+    tax_unit_married: true
     adjusted_gross_income:
       2023: 1_000_000  # IRMAA uses income from 2 years prior
     tax_exempt_interest_income:

policyengine_us/tests/policy/baseline/gov/hhs/medicare/savings_programs/msp_part_b_premium_coverage.yaml

@@ -0,0 +1,29 @@
+- name: MSP part B coverage pays the standard premium for income- and asset-eligible enrollees
+  period: 2025
+  input:
+    medicare_enrolled: true
+    msp_income_eligible: true
+    msp_asset_eligible: true
+    base_part_b_premium: 2_220
+  output:
+    msp_part_b_premium_coverage: 2_220
+
+- name: MSP part B coverage is zero for ineligible enrollees
+  period: 2025
+  input:
+    medicare_enrolled: true
+    msp_income_eligible: false
+    msp_asset_eligible: true
+    base_part_b_premium: 2_220
+  output:
+    msp_part_b_premium_coverage: 0
+
+- name: MSP part B coverage is zero when not enrolled
+  period: 2025
+  input:
+    medicare_enrolled: false
+    msp_income_eligible: true
+    msp_asset_eligible: true
+    base_part_b_premium: 2_220
+  output:
+    msp_part_b_premium_coverage: 0

policyengine_us/tests/policy/baseline/gov/hhs/medicare/test_part_b_msp_offset.py

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+import pytest
+
+from policyengine_us import CountryTaxBenefitSystem, Simulation
+
+
+SYSTEM = CountryTaxBenefitSystem()
+PERIOD = "2025"
+
+
+def make_simulation(
+    *,
+    medicare_enrolled: bool,
+    gross_part_b_premium: float,
+    base_part_b_premium: float,
+    msp_income_eligible: bool,
+    msp_asset_eligible: bool,
+) -> Simulation:
+    return Simulation(
+        tax_benefit_system=SYSTEM,
+        situation={
+            "people": {
+                "person": {
+                    "age": {PERIOD: 65},
+                    "medicare_enrolled": {PERIOD: medicare_enrolled},
+                    "income_adjusted_part_b_premium": {PERIOD: gross_part_b_premium},
+                    "base_part_b_premium": {PERIOD: base_part_b_premium},
+                    "msp_income_eligible": {f"{PERIOD}-01": msp_income_eligible},
+                    "msp_asset_eligible": {f"{PERIOD}-01": msp_asset_eligible},
+                }
+            },
+            "households": {"household": {"members": ["person"]}},
+            "tax_units": {"tax_unit": {"members": ["person"]}},
+            "spm_units": {"spm_unit": {"members": ["person"]}},
+            "families": {"family": {"members": ["person"]}},
+            "marital_units": {"marital_unit": {"members": ["person"]}},
+        },
+    )
+
+
+def test_msp_part_b_premium_coverage_pays_standard_premium():
+    sim = make_simulation(
+        medicare_enrolled=True,
+        gross_part_b_premium=4_440,
+        base_part_b_premium=2_220,
+        msp_income_eligible=True,
+        msp_asset_eligible=True,
+    )
+
+    assert sim.calculate("msp_part_b_premium_coverage", PERIOD)[0] == pytest.approx(
+        2_220
+    )
+
+
+def test_medicare_part_b_premiums_preserve_only_irmaa_above_msp_support():
+    sim = make_simulation(
+        medicare_enrolled=True,
+        gross_part_b_premium=4_440,
+        base_part_b_premium=2_220,
+        msp_income_eligible=True,
+        msp_asset_eligible=True,
+    )
+
+    assert sim.calculate("medicare_part_b_premiums", PERIOD)[0] == pytest.approx(2_220)
+
+
+def test_medicare_part_b_premiums_are_zero_when_msp_covers_standard_premium():
+    sim = make_simulation(
+        medicare_enrolled=True,
+        gross_part_b_premium=2_220,
+        base_part_b_premium=2_220,
+        msp_income_eligible=True,
+        msp_asset_eligible=True,
+    )
+
+    assert sim.calculate("medicare_part_b_premiums", PERIOD)[0] == pytest.approx(0)
+
+
+def test_medicare_part_b_premiums_are_zero_when_not_enrolled():
+    sim = make_simulation(
+        medicare_enrolled=False,
+        gross_part_b_premium=2_220,
+        base_part_b_premium=2_220,
+        msp_income_eligible=True,
+        msp_asset_eligible=True,
+    )
+
+    assert sim.calculate("msp_part_b_premium_coverage", PERIOD)[0] == pytest.approx(0)
+    assert sim.calculate("medicare_part_b_premiums", PERIOD)[0] == pytest.approx(0)

policyengine_us/tests/policy/baseline/household/expense/childcare/spm_unit_capped_work_childcare_expenses.yaml

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+- name: Combined work and childcare expenses are capped at the lower earner
+  period: 2024
+  absolute_error_margin: 0.001
+  input:
+    people:
+      head:
+        age: 35
+        weeks_worked: 10
+        employment_income: 40_000
+        is_household_head: true
+        is_tax_unit_head: true
+      spouse:
+        age: 33
+        weeks_worked: 20
+        employment_income: 2_000
+        is_tax_unit_spouse: true
+      child:
+        age: 8
+    tax_units:
+      tax_unit:
+        members: [head, spouse, child]
+    spm_units:
+      spm_unit:
+        members: [head, spouse, child]
+        spm_unit_pre_subsidy_childcare_expenses: 2_000
+  output:
+    spm_unit_capped_work_childcare_expenses: 2_000
+
+- name: Work expenses are preserved when they already exceed the earnings cap
+  period: 2024
+  absolute_error_margin: 0.001
+  input:
+    people:
+      head:
+        age: 41
+        weeks_worked: 52
+        employment_income: 1_500
+        is_household_head: true
+        is_tax_unit_head: true
+      child:
+        age: 5
+    tax_units:
+      tax_unit:
+        members: [head, child]
+    spm_units:
+      spm_unit:
+        members: [head, child]
+        spm_unit_pre_subsidy_childcare_expenses: 3_000
+  output:
+    spm_unit_capped_work_childcare_expenses: 1_819.714
+
+- name: Childcare is capped by the remaining lower-earner earnings after work expenses
+  period: 2024
+  absolute_error_margin: 0.001
+  input:
+    people:
+      head:
+        age: 46
+        weeks_worked: 52
+        employment_income: 9_098.57
+        is_household_head: true
+        is_tax_unit_head: true
+      spouse:
+        age: 46
+        weeks_worked: 52
+        employment_income: 30_000
+        is_tax_unit_spouse: true
+    tax_units:
+      tax_unit:
+        members: [head, spouse]
+    spm_units:
+      spm_unit:
+        members: [head, spouse]
+        spm_unit_pre_subsidy_childcare_expenses: 21_580
+  output:
+    spm_unit_capped_work_childcare_expenses: 9_098.57
+
+- name: Unmarried partner counts toward the reference person's remaining childcare cap
+  period: 2024
+  absolute_error_margin: 0.001
+  input:
+    people:
+      head:
+        age: 35
+        weeks_worked: 10
+        employment_income: 40_000
+        is_household_head: true
+        is_tax_unit_head: true
+      partner:
+        age: 33
+        weeks_worked: 20
+        employment_income: 2_000
+        is_unmarried_partner_of_household_head: true
+        is_tax_unit_head: true
+      child:
+        age: 8
+    tax_units:
+      reference_unit:
+        members: [head, child]
+      partner_unit:
+        members: [partner]
+    spm_units:
+      spm_unit:
+        members: [head, partner, child]
+        spm_unit_pre_subsidy_childcare_expenses: 2_000
+  output:
+    spm_unit_capped_work_childcare_expenses: 2_000