Implement Montana State Supplementary Payment (SSP)

changelog.d/mt-ssp.added.md

@@ -0,0 +1 @@
+Implemented Montana State Supplementary Payment (SSP).

policyengine_us/parameters/gov/household/household_state_benefits.yaml

@@ -16,6 +16,8 @@ values:
     - ma_state_supplement
     # Michigan benefits
     - mi_ssp
+    # Montana benefits
+    - mt_ssp
     # Colorado benefits
     - co_state_supplement
     - co_oap
@@ -83,6 +85,8 @@ values:
     - ma_state_supplement
     # Michigan benefits
     - mi_ssp
+    # Montana benefits
+    - mt_ssp
     # Colorado benefits
     - co_state_supplement
     - co_oap

policyengine_us/parameters/gov/states/mt/dphhs/ssp/amount/couple.yaml

@@ -0,0 +1,25 @@
+description: Montana provides this amount as the couple state supplement payment under the State Supplementation program.
+
+metadata:
+  unit: currency-USD
+  period: month
+  label: Montana SSP couple payment amount
+  breakdown:
+    - mt_ssp_payment_category
+  reference:
+    - title: SSA POMS SI DEN01415.010, Montana State Supplementary Payments
+      href: https://secure.ssa.gov/poms.nsf/lnx/0501415010DEN
+    - title: SSA State Assistance Programs for SSI Recipients (January 2011), Montana, Table 1
+      href: https://www.ssa.gov/policy/docs/progdesc/ssi_st_asst/2011/mt.html
+
+# Couple totals (not per-spouse). ARM 37.43.104 lists individual rates
+# only; couple rates are published only in SSA POMS and the SSA 2011
+# report (couple = 2x individual + $5). Frozen since January 1989.
+ASSISTED_LIVING_OR_GROUP_OR_COMMUNITY_HOME:
+  1989-01-01: 193
+FOSTER_CARE:
+  1989-01-01: 110.50
+TRANSITIONAL_LIVING:
+  1989-01-01: 57
+NONE:
+  1989-01-01: 0

policyengine_us/parameters/gov/states/mt/dphhs/ssp/amount/individual.yaml

@@ -0,0 +1,25 @@
+description: Montana provides this amount as the individual state supplement payment under the State Supplementation program.
+
+metadata:
+  unit: currency-USD
+  period: month
+  label: Montana SSP individual payment amount
+  breakdown:
+    - mt_ssp_payment_category
+  reference:
+    - title: ARM 37.43.104(1), Payment Standards
+      href: https://www.law.cornell.edu/regulations/montana/ARM-37-43-104
+    - title: SSA POMS SI DEN01415.010, Montana State Supplementary Payments
+      href: https://secure.ssa.gov/poms.nsf/lnx/0501415010DEN
+    - title: SSA State Assistance Programs for SSI Recipients (January 2011), Montana, Table 1
+      href: https://www.ssa.gov/policy/docs/progdesc/ssi_st_asst/2011/mt.html
+
+# Rates frozen since January 1989 per SSA POMS SI DEN01415.010.
+ASSISTED_LIVING_OR_GROUP_OR_COMMUNITY_HOME:
+  1989-01-01: 94
+FOSTER_CARE:
+  1989-01-01: 52.75
+TRANSITIONAL_LIVING:
+  1989-01-01: 26
+NONE:
+  1989-01-01: 0

policyengine_us/programs.yaml

@@ -707,6 +707,12 @@ programs:
         full_name: Michigan State Supplementary Payment
         variable: mi_ssp
         parameter_prefix: gov.states.mi.mdhhs.ssp
+      - state: MT
+        status: complete
+        name: Montana SSP
+        full_name: Montana State Supplementation
+        variable: mt_ssp
+        parameter_prefix: gov.states.mt.dphhs.ssp
       - state: ME
         status: complete
         name: Maine SSP

policyengine_us/tests/policy/baseline/gov/states/mt/dphhs/ssp/edge_cases.yaml

@@ -0,0 +1,179 @@
+- name: Case 1, uncapped_ssi exactly $0 (boundary, strict greater-than) is ineligible.
+  absolute_error_margin: 0.01
+  period: 2024-01
+  input:
+    people:
+      person1:
+        # Boundary: uncapped_ssi == 0 fails the strict (uncapped_ssi > 0) gate.
+        uncapped_ssi: 0
+        mt_ssp_payment_category: ASSISTED_LIVING_OR_GROUP_OR_COMMUNITY_HOME
+    spm_units:
+      spm_unit:
+        members: [person1]
+    households:
+      household:
+        members: [person1]
+        state_code: MT
+  output:
+    mt_ssp_eligible: false
+    mt_ssp: 0
+
+- name: Case 2, uncapped_ssi exactly $0.01 (smallest positive value) is eligible.
+  absolute_error_margin: 0.01
+  period: 2024-01
+  input:
+    people:
+      person1:
+        # Annual $0.01 -> monthly ~$0.000833 in the MONTH formula; still > 0
+        # so eligibility passes. Spillover deduction = max_(0, -uncapped_ssi)
+        # = 0 since uncapped_ssi is positive, so full individual rate applies.
+        uncapped_ssi: 0.01
+        mt_ssp_payment_category: TRANSITIONAL_LIVING
+    spm_units:
+      spm_unit:
+        members: [person1]
+    households:
+      household:
+        members: [person1]
+        state_code: MT
+  output:
+    # K tier individual = $26 - $0 spillover = $26.
+    mt_ssp_eligible: true
+    mt_ssp: 26
+
+- name: Case 3, federal SSI payment is $0 but uncapped_ssi positive (income just below FBR) is eligible.
+  absolute_error_margin: 0.01
+  period: 2024-01
+  input:
+    people:
+      person1:
+        # Group 2 path: categorically eligible, federal SSI takeup zeros the
+        # actual payment, uncapped_ssi remains positive (income just below the
+        # federal SSI cutoff). Distinct from Case 10 of integration.yaml: this
+        # case explicitly verifies the (ssi == 0, uncapped_ssi > 0) boundary.
+        is_ssi_eligible: true
+        ssi: 0
+        uncapped_ssi: 12
+        mt_ssp_payment_category: ASSISTED_LIVING_OR_GROUP_OR_COMMUNITY_HOME
+    spm_units:
+      spm_unit:
+        members: [person1]
+    households:
+      household:
+        members: [person1]
+        state_code: MT
+  output:
+    # uncapped_ssi annual $12 -> monthly $1; spillover = max_(0, -1) = 0;
+    # G/H/I tier = $94 - $0 = $94.
+    mt_ssp_eligible: true
+    mt_ssp: 94
+
+- name: Case 4, single ineligible person (NONE category) returns zero benefit.
+  absolute_error_margin: 0.01
+  period: 2024-01
+  input:
+    people:
+      person1:
+        is_ssi_eligible: true
+        mt_ssp_payment_category: NONE
+    spm_units:
+      spm_unit:
+        members: [person1]
+    households:
+      household:
+        members: [person1]
+        state_code: MT
+  output:
+    # NONE category fails the qualifying-arrangement gate.
+    mt_ssp_eligible: false
+    mt_ssp: 0
+
+- name: Case 5, three eligible persons in same SPM unit (parent, adult child, grandparent) sums correctly.
+  absolute_error_margin: 0.01
+  period: 2024-01
+  input:
+    people:
+      person1:
+        # Aged grandparent in personal care facility.
+        age: 80
+        is_ssi_eligible: true
+        is_ssi_aged_blind_disabled: true
+        mt_ssp_payment_category: ASSISTED_LIVING_OR_GROUP_OR_COMMUNITY_HOME
+      person2:
+        # Disabled parent in foster care.
+        age: 50
+        is_ssi_eligible: true
+        is_ssi_aged_blind_disabled: true
+        mt_ssp_payment_category: FOSTER_CARE
+      person3:
+        # Disabled adult child in transitional living.
+        age: 28
+        is_ssi_eligible: true
+        is_ssi_aged_blind_disabled: true
+        mt_ssp_payment_category: TRANSITIONAL_LIVING
+    marital_units:
+      marital_unit1:
+        members: [person1]
+      marital_unit2:
+        members: [person2]
+      marital_unit3:
+        members: [person3]
+    spm_units:
+      spm_unit:
+        members: [person1, person2, person3]
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: MT
+  output:
+    # Three separate marital units -> each gets individual rate.
+    # person1: G/H/I = $94; person2: J = $52.75; person3: K = $26.
+    # SPM total = $94 + $52.75 + $26 = $172.75.
+    mt_ssp_eligible: [true, true, true]
+    mt_ssp: 172.75
+
+- name: Case 6, January period for a person who would move state mid-year still uses MT inputs.
+  absolute_error_margin: 0.01
+  period: 2024-01
+  input:
+    people:
+      person1:
+        # Period format restriction: only 2024-01 or 2024 are supported, so we
+        # cannot model a mid-year move directly. This case documents that for
+        # the January snapshot, the state_code: MT input controls the result.
+        is_ssi_eligible: true
+        mt_ssp_payment_category: FOSTER_CARE
+    spm_units:
+      spm_unit:
+        members: [person1]
+    households:
+      household:
+        members: [person1]
+        state_code: MT
+  output:
+    # January snapshot with MT state code -> J tier individual = $52.75.
+    mt_ssp_eligible: true
+    mt_ssp: 52.75
+
+- name: Case 7, high earnings make person SSI-ineligible (uncapped_ssi=0) so MT SSP is zero.
+  absolute_error_margin: 0.01
+  period: 2024-01
+  input:
+    people:
+      person1:
+        # High employment income -> not SSI-eligible at all -> uncapped_ssi=0
+        # (uncapped_ssi has defined_for="is_ssi_eligible"). The boundary case
+        # demonstrates that when SSI eligibility itself fails, MT SSP correctly
+        # returns zero rather than inflating from the spillover deduction.
+        employment_income: 60_000
+        mt_ssp_payment_category: ASSISTED_LIVING_OR_GROUP_OR_COMMUNITY_HOME
+    spm_units:
+      spm_unit:
+        members: [person1]
+    households:
+      household:
+        members: [person1]
+        state_code: MT
+  output:
+    mt_ssp_eligible: false
+    mt_ssp: 0