Add marketplace selected-plan PTC proxy variables

changelog.d/marketplace-selected-plan-ptc-proxy.added.md

@@ -0,0 +1 @@
+Added ACA selected-plan marketplace proxy variables for benchmark ratio inputs and used versus unused premium tax credit analysis.

policyengine_us/tests/policy/baseline/gov/aca/ptc/integration.yaml

@@ -61,3 +61,32 @@
     slcsp: 4_911.564 #kff says 4,916 
     aca_magi_fraction: 1.99  # 30k / 15,060 (approx. prior-year FPL reference)
     aca_ptc: 4_323.56
+
+- name: 2025 aca_ptc_los_angeles_single_selected_plan_ratio
+  absolute_error_margin: 0.01
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 40
+        employment_income: 30_000
+        is_aca_eshi_eligible: false
+    tax_units:
+      tax_unit:
+        members: [person1]
+        selected_marketplace_plan_benchmark_ratio: 0.8
+    households:
+      household:
+        members: [person1]
+        state_fips: 6  # CA
+        county: LOS_ANGELES_COUNTY_CA
+        three_digit_zip_code: 902  # 90210 -> rating area 16 in CA
+  output:
+    is_medicaid_eligible: [false]
+    is_aca_ptc_eligible: [true]
+    slcsp: 4_911.564 #kff says 4,916 
+    aca_magi_fraction: 1.99  # 30k / 15,060 (approx. prior-year FPL reference)
+    aca_ptc: 4_323.56
+    selected_marketplace_plan_premium_proxy: 3_929.25
+    used_aca_ptc: 3_929.25
+    unused_aca_ptc: 394.31

policyengine_us/tests/policy/baseline/gov/aca/ptc/selected_marketplace_plan_premium_proxy.yaml

@@ -0,0 +1,34 @@
+- name: Case 1, selected plan proxy defaults to the benchmark premium.
+  absolute_error_margin: 0.01
+  period: 2025
+  input:
+    is_aca_ptc_eligible: true
+    slcsp: 1_200
+    aca_magi: 25_000
+    aca_required_contribution_percentage: 0.04
+  output:
+    selected_marketplace_plan_premium_proxy: 1_200
+
+- name: Case 2, selected plan proxy scales with the selected plan ratio.
+  absolute_error_margin: 0.01
+  period: 2025
+  input:
+    is_aca_ptc_eligible: true
+    slcsp: 10_000
+    aca_magi: 20_000
+    aca_required_contribution_percentage: 0.04
+    selected_marketplace_plan_benchmark_ratio: 0.8
+  output:
+    selected_marketplace_plan_premium_proxy: 8_000
+
+- name: Case 3, selected plan proxy is zero when no ACA PTC is available.
+  absolute_error_margin: 0.01
+  period: 2025
+  input:
+    is_aca_ptc_eligible: true
+    slcsp: 1_200
+    aca_magi: 25_000
+    aca_required_contribution_percentage: 0.05
+    selected_marketplace_plan_benchmark_ratio: 0.8
+  output:
+    selected_marketplace_plan_premium_proxy: 0

policyengine_us/tests/policy/baseline/gov/aca/ptc/used_aca_ptc.yaml

@@ -0,0 +1,41 @@
+- name: Case 1, benchmark-plan selection uses the full ACA PTC.
+  absolute_error_margin: 0.01
+  period: 2025
+  input:
+    is_aca_ptc_eligible: true
+    slcsp: 1_200
+    aca_magi: 25_000
+    aca_required_contribution_percentage: 0.04
+  output:
+    aca_ptc: 200
+    used_aca_ptc: 200
+    unused_aca_ptc: 0
+
+- name: Case 2, a bronze-like ratio leaves some ACA PTC unused.
+  absolute_error_margin: 0.01
+  period: 2025
+  input:
+    is_aca_ptc_eligible: true
+    slcsp: 10_000
+    aca_magi: 20_000
+    aca_required_contribution_percentage: 0.04
+    selected_marketplace_plan_benchmark_ratio: 0.8
+  output:
+    aca_ptc: 9_200
+    selected_marketplace_plan_premium_proxy: 8_000
+    used_aca_ptc: 8_000
+    unused_aca_ptc: 1_200
+
+- name: Case 3, used and unused ACA PTC are zero when ACA PTC is zero.
+  absolute_error_margin: 0.01
+  period: 2025
+  input:
+    is_aca_ptc_eligible: true
+    slcsp: 1_200
+    aca_magi: 25_000
+    aca_required_contribution_percentage: 0.05
+    selected_marketplace_plan_benchmark_ratio: 0.8
+  output:
+    aca_ptc: 0
+    used_aca_ptc: 0
+    unused_aca_ptc: 0

policyengine_us/variables/gov/aca/ptc/selected_marketplace_plan_benchmark_ratio.py

@@ -0,0 +1,10 @@
+from policyengine_us.model_api import *
+
+
+class selected_marketplace_plan_benchmark_ratio(Variable):
+    value_type = float
+    entity = TaxUnit
+    label = "Selected marketplace plan premium to benchmark premium ratio"
+    unit = "/1"
+    definition_period = YEAR
+    default_value = 1.0

policyengine_us/variables/gov/aca/ptc/selected_marketplace_plan_premium_proxy.py

@@ -0,0 +1,18 @@
+from policyengine_us.model_api import *
+
+
+class selected_marketplace_plan_premium_proxy(Variable):
+    value_type = float
+    entity = TaxUnit
+    label = "Selected marketplace plan premium proxy"
+    unit = USD
+    definition_period = YEAR
+
+    def formula(tax_unit, period, parameters):
+        aca_ptc = tax_unit("aca_ptc", period)
+        return where(
+            aca_ptc > 0,
+            tax_unit("slcsp", period)
+            * tax_unit("selected_marketplace_plan_benchmark_ratio", period),
+            0,
+        )

policyengine_us/variables/gov/aca/ptc/unused_aca_ptc.py

@@ -0,0 +1,12 @@
+from policyengine_us.model_api import *
+
+
+class unused_aca_ptc(Variable):
+    value_type = float
+    entity = TaxUnit
+    label = "Unused ACA premium tax credit"
+    unit = USD
+    definition_period = YEAR
+
+    def formula(tax_unit, period, parameters):
+        return max_(0, tax_unit("aca_ptc", period) - tax_unit("used_aca_ptc", period))

policyengine_us/variables/gov/aca/ptc/used_aca_ptc.py

@@ -0,0 +1,15 @@
+from policyengine_us.model_api import *
+
+
+class used_aca_ptc(Variable):
+    value_type = float
+    entity = TaxUnit
+    label = "Used ACA premium tax credit"
+    unit = USD
+    definition_period = YEAR
+
+    def formula(tax_unit, period, parameters):
+        return min_(
+            tax_unit("aca_ptc", period),
+            tax_unit("selected_marketplace_plan_premium_proxy", period),
+        )