Implement Michigan Family Independence Program (FIP)

[hua7450]

Summary

Implements Michigan Family Independence Program (FIP), the state's TANF cash assistance program, with dual-test system and per-person deductions verified against BEM policy manuals.

Closes #6813

Status

• [x] Documentation collected
• [x] Parameters created (6 files)
• [x] Variables implemented (11 files)
• [x] Tests written (66 test cases across 8 files)
• [x] CI passing
• [x] Dual-test system implemented (20% initial, 50% benefit)
• [x] Per-person deduction logic verified
• [x] Formulas verified against BEM 518, 520, 503
• [x] Ready for review

---

Key Changes

Implementation Summary

• ✅ 11 new variables for Michigan FIP benefit calculation
• ✅ 6 parameter files with dual deduction rates and historical values
• ✅ 66 comprehensive test cases across 8 test files (17 integration + 49 unit)
• ✅ Dual-test system correctly separates eligibility from benefit calculation
• ✅ All tests passing

Correct Formula (Per BEM 518 and BEM 520)

Earned Income Deduction (per person):
  Flat: $200 per working person
  Percentage: 20% OR 50% depending on purpose
  
Initial Eligibility (new applicants - BEM 520 Section C):
  - Uses 20% deduction rate (Qualifying Deficit Test)
  - Determines IF household qualifies
  
Benefit Calculation (everyone - BEM 520 Section D):
  - Uses 50% deduction rate (Issuance Deficit Test)
  - Determines HOW MUCH benefit
  - Applies to both new applicants and enrolled recipients
  
Countable Income = Sum(per-person countable earned) + gross unearned
Monthly Benefit = MAX(Payment Standard - Countable Income, 0)

Critical Implementation Details:

1. Deductions apply per person (each worker gets their own $200)
2. Initial eligibility test (20%) is separate from benefit calculation (50%)
3. Once qualified, everyone gets benefits calculated with 50% rate

---

Files Added

Parameters (6 files)

policyengine_us/parameters/gov/states/mi/mdhhs/fip/
├── resource_limit.yaml
├── income/deductions/earned_income_disregard/
│   ├── flat_amount.yaml                            # $200
│   ├── initial_percent.yaml                        # 20% (eligibility only)
│   └── ongoing_percent.yaml                        # 50% (benefit calc, since 2011)
└── payment_standard/
    ├── amounts.yaml                                # Historical 2017 & 2025
    └── additional_person_increment.yaml            # $80→$95

Variables (11 files)

policyengine_us/variables/gov/states/mi/mdhhs/fip/
├── eligibility/
│   ├── mi_fip_eligible.py
│   ├── mi_fip_income_eligible.py                   # Dual-test logic!
│   └── mi_fip_resources_eligible.py
├── income/
│   ├── mi_fip_earned_income_after_deductions_person.py         # 50% (benefit)
│   ├── mi_fip_earned_income_after_deductions_initial_person.py # 20% (eligibility)
│   ├── mi_fip_countable_earned_income.py           # Uses adds pattern (50%)
│   ├── mi_fip_countable_earned_income_initial.py   # Uses adds pattern (20%)
│   ├── mi_fip_countable_income.py                  # Uses adds (50% version)
│   └── mi_fip_countable_income_initial.py          # Uses adds (20% version)
├── mi_fip.py
└── mi_fip_payment_standard.py

Tests (8 files, 66 test cases)

policyengine_us/tests/policy/baseline/gov/states/mi/mdhhs/fip/
├── eligibility/
│   ├── mi_fip_eligible.yaml                        # 5 tests
│   ├── mi_fip_income_eligible.yaml                 # 7 tests (tests both 20% & 50%)
│   └── mi_fip_resources_eligible.yaml              # 6 tests
├── income/
│   ├── mi_fip_countable_earned_income.yaml         # 8 tests (50% benefit calc)
│   └── mi_fip_countable_income.yaml                # 6 tests
├── integration.yaml                                # 17 integration tests
├── mi_fip.yaml                                     # 7 benefit tests
└── mi_fip_payment_standard.yaml                    # 10 payment tests

---

Example Calculations

New Applicant: Two-Step Process

Household: Family of 3, NEW applicant, $600/month earned

STEP 1: Initial Eligibility Test (20% deduction)
  Countable = $600 - [$200 + 20%×$400] = $600 - $280 = $320
  Payment Standard = $583
  $320 < $583 → PASSES (eligible for FIP)

STEP 2: Benefit Calculation (50% deduction)
  Countable = $600 - [$200 + 50%×$400] = $600 - $400 = $200
  Benefit = $583 - $200 = $383/month

Enrolled Recipient: One-Step Process

Household: Family of 3, ENROLLED, $1,000/month earned

Initial eligibility: Already passed (enrolled)

Benefit Calculation (50% deduction):
  Countable = $1,000 - [$200 + 50%×$800] = $1,000 - $600 = $400
  Payment Standard = $583
  Benefit = $583 - $400 = $183/month

Multiple Earners - Per-Person Deductions

Household: 2 parents + 2 children, ENROLLED
Income: $800 + $400 = $1,200 total

BEM 518: "Apply separately to each program group member"

Parent 1: $800 - [$200 + 50%×$600] = $300 countable
Parent 2: $400 - [$200 + 50%×$200] = $100 countable
Total countable = $400

Payment Standard (size 4) = $707  
Benefit = $707 - $400 = $307/month

---

Testing & Verification

Test Results

✅ All 66 tests passing
   - 17 integration tests  
   - 49 unit tests
   - 0 failures

Legal Verification

All formulas verified against:

• ✅ BEM 518 (BPB 2023-013, effective 7-1-2023)
• ✅ BEM 520 (BPB 2023-002, effective 1-1-2023)
• ✅ BEM 503 (BPB 2025-022, effective 10-1-2025)
• ✅ Michigan TANF State Plan 2017 (2008 frozen amounts)
• ✅ Michigan TANF State Plan 2025 (2024 increased amounts)

---

Recent Formula Corrections

Commit History

1. ✅ Per-person deduction logic (each worker gets own $200)
2. ✅ Dual-test system (20% eligibility, 50% benefit)
3. ✅ Historical payment standards (2008 & 2025)
4. ✅ Proper use of adds pattern
5. ✅ Verified against BEM manuals

---

🤖 Generated with Claude Code

Co-Authored-By: Claude [email protected]

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 100.00%. Comparing base (ba52386) to head (a40f9bd). :warning: Report is 42 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##            master     #6812    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files            2        11     +9     
  Lines           26       147   +121     
==========================================
+ Hits            26       147   +121     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

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