Massachusetts TAFDC: the dependent care deduction is subtracted per earner (twice for two non-joint earners, half lost for a one-earner joint return)

Start by locating ma_tafdc_partially_disregarded_earned_income and the SPM-unit dependent-care deduction calculation; inspect the related TANF Massachusetts tests. Reproduce the one-earner joint-return and two-earner separate-return cases in the issue, then verify the unit-level deduction is applied only once and the resulting grant amounts match the stated expectations.

Summary

ma_tafdc_partially_disregarded_earned_income (Person) subtracts the SPM unit's whole dependent care deduction from each person's half-disregarded earnings, or half of it for each person on a joint return (the code comment says it attributes the deduction "equally to each spouse if filing jointly"):

dependent_care_deduction = person.spm_unit("ma_tafdc_dependent_care_deduction", period)
applicable_dependent_care_deduction = where(joint, dependent_care_deduction / 2, dependent_care_deduction)
return max_(0, earned_income_after_work_related_deduction * p.percentage - applicable_dependent_care_deduction)

Each person's result is floored at zero and then summed over the unit for the grant. So:

• a married couple filing jointly where one spouse works deducts only half of the cost (the other half is subtracted from the non-earner's zero earnings and lost to the floor);
• a unit with two earners who are not on one joint return (for example unmarried parents with separate tax units) deducts the same cost from each earner.

106 CMR 704.275(A): the deduction is "made after the 50% disregard", for full-time work "the actual cost of dependent care ... but shall not exceed $175 per dependent child, age two or older, or incapacitated individual per month" ($200 under age two), and "In all situations, the amount allowed for dependent care is the actual expenditure for dependent care ... or the maximum allowable deduction, whichever is less." The unit's total deduction is the cost (up to the maximum), not the cost per earner or half of it.

Reproduction

Same results on policyengine-us 1.811.2 (45d51ef5d4) and on main (26348e7cf7).

One earner on a joint return:

from policyengine_us import Simulation
sim = Simulation(situation={
    "people": {"a": {"age": {2025: 30}, "employment_income": {2025: 12_000}, "weekly_hours_worked_before_lsr": {2025: 40}},
               "b": {"age": {2025: 30}}, "c": {"age": {2025: 1}}},
    "tax_units": {"t": {"members": ["a", "b", "c"]}},
    "marital_units": {"m": {"members": ["a", "b"]}},
    "spm_units": {"s": {"members": ["a", "b", "c"], "is_tanf_enrolled": {2025: True},
                        "spm_unit_pre_subsidy_childcare_expenses": {2025: 3_000}}},
    "households": {"h": {"members": ["a", "b", "c"], "state_name": {2025: "MA"}}},
})
sim.calculate("ma_tafdc_dependent_care_deduction", "2025-01")             # 200
sim.calculate("ma_tafdc_partially_disregarded_earned_income", "2025-01")  # [300, 0, 0]: 0.5 x (1,000 - 200) - 100
sim.calculate("ma_tafdc", 2025)                                           # 9,278

Expected: 0.5 x (1,000 - 200) - 200 = $200 a month after the disregards. With the six-month 100% disregard that is $100 a month on average instead of $150, so the grant is $50 a month higher: $9,878 a year.

Two earners on separate returns:

sim = Simulation(situation={
    "people": {"a": {"age": {2025: 30}, "employment_income": {2025: 8_400}, "weekly_hours_worked_before_lsr": {2025: 40}},
               "b": {"age": {2025: 30}, "employment_income": {2025: 8_400}, "weekly_hours_worked_before_lsr": {2025: 40}},
               "c": {"age": {2025: 1}}},
    "tax_units": {"t1": {"members": ["a", "c"]}, "t2": {"members": ["b"]}},
    "spm_units": {"s": {"members": ["a", "b", "c"], "is_tanf_enrolled": {2025: True},
                        "spm_unit_pre_subsidy_childcare_expenses": {2025: 3_000}}},
    "households": {"h": {"members": ["a", "b", "c"], "state_name": {2025: "MA"}}},
})
sim.calculate("ma_tafdc_dependent_care_deduction", "2025-01")             # 200
sim.calculate("ma_tafdc_partially_disregarded_earned_income", "2025-01")  # [50, 50, 0]: 0.5 x (700 - 200) - 200, each
sim.calculate("ma_tafdc", 2025)                                           # 10,478

Expected: 0.5 x 500 + 0.5 x 500 - 200 = $300 a month (PE deducts $400 for a $200 cost). With the six-month 100% disregard the expected grant is $100 a month lower on average than PE's: $9,278 a year.

Possible fix

Subtract the unit's deduction once: at the SPM unit, from the sum of the members' half-disregarded earnings (max_(sum - dependent_care_deduction, 0)), or allocate it to earners in proportion to their earnings.

Impact

PRD comparison (2025 aligned view, shared set): 4 Massachusetts SPM units, -$4,778 of PE - PRD (2026: 3 units, -$4,800). Cause tanf_ma_dependent_care_split.