diff --git a/changelog.d/fix-9983-ma-tafdc-dependent-care-once.fixed.md b/changelog.d/fix-9983-ma-tafdc-dependent-care-once.fixed.md
new file mode 100644
index 00000000000..afa48002aaa
--- /dev/null
+++ b/changelog.d/fix-9983-ma-tafdc-dependent-care-once.fixed.md
@@ -0,0 +1 @@
+Subtract the Massachusetts TAFDC dependent care deduction once, after the 50% disregard, from the earnings of the member who pays for the care (106 CMR 704.275(A)), instead of from each earner (or half of it from each spouse on a joint return). A new input, `ma_tafdc_dependent_care_payer`, names the payer; by default it is the head or spouse with the highest gross earnings.
diff --git a/policyengine_us/tests/policy/baseline/gov/states/ma/dta/tcap/tafdc/income/deductions/ma_tafdc_dependent_care_payer.yaml b/policyengine_us/tests/policy/baseline/gov/states/ma/dta/tcap/tafdc/income/deductions/ma_tafdc_dependent_care_payer.yaml
new file mode 100644
index 00000000000..2b820568200
--- /dev/null
+++ b/policyengine_us/tests/policy/baseline/gov/states/ma/dta/tcap/tafdc/income/deductions/ma_tafdc_dependent_care_payer.yaml
@@ -0,0 +1,108 @@
+# Unless a case names the payer, the payer is the head or spouse with the
+# highest gross earnings, and the first such member when earnings are equal.
+
+- name: One earner on a joint return pays
+  period: 2026
+  input:
+    people:
+      parent1:
+        age: 30
+        employment_income_before_lsr: 12_000
+      parent2:
+        age: 30
+      child:
+        age: 1
+    tax_units:
+      tax_unit:
+        members: [parent1, parent2, child]
+    marital_units:
+      marital_unit:
+        members: [parent1, parent2]
+    spm_units:
+      spm_unit:
+        members: [parent1, parent2, child]
+    households:
+      household:
+        members: [parent1, parent2, child]
+        state_code: MA
+  output:
+    ma_tafdc_dependent_care_payer: [true, false, false]
+
+- name: The higher earner pays, even when listed second
+  period: 2026
+  input:
+    people:
+      parent1:
+        age: 30
+        employment_income_before_lsr: 4_800
+      parent2:
+        age: 30
+        employment_income_before_lsr: 12_000
+      child:
+        age: 1
+    tax_units:
+      tax_unit1:
+        members: [parent1, child]
+      tax_unit2:
+        members: [parent2]
+    spm_units:
+      spm_unit:
+        members: [parent1, parent2, child]
+    households:
+      household:
+        members: [parent1, parent2, child]
+        state_code: MA
+  output:
+    ma_tafdc_dependent_care_payer: [false, true, false]
+
+- name: Equal earners, the first one pays
+  period: 2026
+  input:
+    people:
+      parent1:
+        age: 30
+        employment_income_before_lsr: 8_400
+      parent2:
+        age: 30
+        employment_income_before_lsr: 8_400
+      child:
+        age: 1
+    tax_units:
+      tax_unit1:
+        members: [parent1, child]
+      tax_unit2:
+        members: [parent2]
+    spm_units:
+      spm_unit:
+        members: [parent1, parent2, child]
+    households:
+      household:
+        members: [parent1, parent2, child]
+        state_code: MA
+  output:
+    ma_tafdc_dependent_care_payer: [true, false, false]
+
+- name: A dependent teen with higher earnings is not the payer
+  period: 2026
+  input:
+    people:
+      parent:
+        age: 40
+        employment_income_before_lsr: 6_000
+      teen:
+        age: 16
+        employment_income_before_lsr: 9_000
+      child:
+        age: 1
+    tax_units:
+      tax_unit:
+        members: [parent, teen, child]
+    spm_units:
+      spm_unit:
+        members: [parent, teen, child]
+    households:
+      household:
+        members: [parent, teen, child]
+        state_code: MA
+  output:
+    ma_tafdc_dependent_care_payer: [true, false, false]
diff --git a/policyengine_us/tests/policy/baseline/gov/states/ma/dta/tcap/tafdc/income/earned/ma_tafdc_partially_disregarded_earned_income.yaml b/policyengine_us/tests/policy/baseline/gov/states/ma/dta/tcap/tafdc/income/earned/ma_tafdc_partially_disregarded_earned_income.yaml
index 0c856c677d3..d540a9aa964 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/ma/dta/tcap/tafdc/income/earned/ma_tafdc_partially_disregarded_earned_income.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/ma/dta/tcap/tafdc/income/earned/ma_tafdc_partially_disregarded_earned_income.yaml
@@ -30,3 +30,405 @@
     state_code: MA
   output:
     ma_tafdc_partially_disregarded_earned_income: 0
+
+# 106 CMR 704.275(A): an employed applicant or client "may receive a deduction
+# from income equal to the expenditure for the care of a dependent child", made
+# after the 50% disregard, and "the amount allowed for dependent care is the
+# actual expenditure for dependent care ... or the maximum allowable deduction,
+# whichever is less." DTA's BEACON help uses it "as a deduction for the client
+# incurring the expense". The unit's deduction is subtracted once, from the
+# earnings of the member who pays (ma_tafdc_dependent_care_payer). A part above
+# the payer's earnings does not reduce another member's earnings. Unless a case
+# names the payer, the payer is the head or spouse with the highest gross
+# earnings (the first such member when earnings are equal).
+# Unless a case says otherwise, the child is age 1 and the unit works full
+# time, so the maximum is $200 a month; care costs $3,000 a year ($250 a
+# month), so the unit's deduction is $200 a month.
+
+- name: One earner on a joint return, the deduction is subtracted in full once
+  period: 2026-01
+  input:
+    people:
+      parent1:
+        age: 30
+        employment_income_before_lsr: 12_000  # $1,000/month
+        weekly_hours_worked_before_lsr: 40
+      parent2:
+        age: 30
+      child:
+        age: 1
+    tax_units:
+      tax_unit:
+        members: [parent1, parent2, child]
+    marital_units:
+      marital_unit:
+        members: [parent1, parent2]
+    spm_units:
+      spm_unit:
+        members: [parent1, parent2, child]
+        is_tanf_enrolled: true
+        spm_unit_pre_subsidy_childcare_expenses: 3_000
+    households:
+      household:
+        members: [parent1, parent2, child]
+        state_code: MA
+  output:
+    ma_tafdc_dependent_care_deduction: 200
+    ma_tafdc_dependent_care_payer: [true, false, false]
+    # parent1: ($1,000 - $200 work expense) x 0.5 = $400; $400 - $200 = $200.
+    # Before, half of the $200 was assigned to parent2, who has no earnings,
+    # and was lost: $400 - $100 = $300.
+    ma_tafdc_partially_disregarded_earned_income: [200, 0, 0]
+
+- name: Two equal earners on separate returns, the deduction is subtracted once from the payer
+  period: 2026-01
+  input:
+    people:
+      parent1:
+        age: 30
+        employment_income_before_lsr: 8_400  # $700/month
+        weekly_hours_worked_before_lsr: 40
+      parent2:
+        age: 30
+        employment_income_before_lsr: 8_400  # $700/month
+        weekly_hours_worked_before_lsr: 40
+      child:
+        age: 1
+    tax_units:
+      tax_unit1:
+        members: [parent1, child]
+      tax_unit2:
+        members: [parent2]
+    spm_units:
+      spm_unit:
+        members: [parent1, parent2, child]
+        is_tanf_enrolled: true
+        spm_unit_pre_subsidy_childcare_expenses: 3_000
+    households:
+      household:
+        members: [parent1, parent2, child]
+        state_code: MA
+  output:
+    ma_tafdc_dependent_care_deduction: 200
+    # Equal earnings, so the payer is the first of the two.
+    ma_tafdc_dependent_care_payer: [true, false, false]
+    # Each: ($700 - $200) x 0.5 = $250. parent1 pays: $250 - $200 = $50;
+    # parent2 keeps $250. Unit total $300. Before, each earner had the full
+    # $200 subtracted: $50 each, $400 deducted for a $200 cost.
+    ma_tafdc_partially_disregarded_earned_income: [50, 250, 0]
+
+- name: Two unequal earners, the payer is not named, so the higher earner pays
+  period: 2026-01
+  input:
+    people:
+      parent1:
+        age: 30
+        employment_income_before_lsr: 12_000  # $1,000/month
+        weekly_hours_worked_before_lsr: 40
+      parent2:
+        age: 30
+        employment_income_before_lsr: 4_800  # $400/month
+        weekly_hours_worked_before_lsr: 40
+      child:
+        age: 1
+    tax_units:
+      tax_unit1:
+        members: [parent1, child]
+      tax_unit2:
+        members: [parent2]
+    spm_units:
+      spm_unit:
+        members: [parent1, parent2, child]
+        is_tanf_enrolled: true
+        spm_unit_pre_subsidy_childcare_expenses: 3_000
+    households:
+      household:
+        members: [parent1, parent2, child]
+        state_code: MA
+  output:
+    ma_tafdc_dependent_care_payer: [true, false, false]
+    # parent1: ($1,000 - $200) x 0.5 = $400; parent2: ($400 - $200) x 0.5 = $100.
+    # parent1 pays: $400 - $200 = $200; parent2 keeps $100. Unit total $300.
+    ma_tafdc_partially_disregarded_earned_income: [200, 100, 0]
+
+- name: Two unequal earners, the lower earner pays and cannot use the whole deduction
+  period: 2026-01
+  input:
+    people:
+      parent1:
+        age: 30
+        employment_income_before_lsr: 12_000  # $1,000/month
+        weekly_hours_worked_before_lsr: 40
+        ma_tafdc_dependent_care_payer: false
+      parent2:
+        age: 30
+        employment_income_before_lsr: 4_800  # $400/month
+        weekly_hours_worked_before_lsr: 40
+        ma_tafdc_dependent_care_payer: true
+      child:
+        age: 1
+        ma_tafdc_dependent_care_payer: false
+    tax_units:
+      tax_unit1:
+        members: [parent1, child]
+      tax_unit2:
+        members: [parent2]
+    spm_units:
+      spm_unit:
+        members: [parent1, parent2, child]
+        is_tanf_enrolled: true
+        spm_unit_pre_subsidy_childcare_expenses: 3_000
+    households:
+      household:
+        members: [parent1, parent2, child]
+        state_code: MA
+  output:
+    ma_tafdc_dependent_care_deduction: 200
+    # parent1: $400 after the disregard; parent2: $100 after the disregard.
+    # parent2 pays: max($100 - $200, 0) = $0. The other $100 of the deduction
+    # does not reduce parent1's earnings: parent1 keeps $400. Unit total $400.
+    ma_tafdc_partially_disregarded_earned_income: [400, 0, 0]
+
+- name: Two members set as payers share the deduction equally
+  period: 2026-01
+  input:
+    people:
+      parent1:
+        age: 30
+        employment_income_before_lsr: 12_000  # $1,000/month
+        weekly_hours_worked_before_lsr: 40
+        ma_tafdc_dependent_care_payer: true
+      parent2:
+        age: 30
+        employment_income_before_lsr: 4_800  # $400/month
+        weekly_hours_worked_before_lsr: 40
+        ma_tafdc_dependent_care_payer: true
+      child:
+        age: 1
+        ma_tafdc_dependent_care_payer: false
+    tax_units:
+      tax_unit1:
+        members: [parent1, child]
+      tax_unit2:
+        members: [parent2]
+    spm_units:
+      spm_unit:
+        members: [parent1, parent2, child]
+        is_tanf_enrolled: true
+        spm_unit_pre_subsidy_childcare_expenses: 3_000
+    households:
+      household:
+        members: [parent1, parent2, child]
+        state_code: MA
+  output:
+    # $200 / 2 = $100 each. parent1: $400 - $100 = $300;
+    # parent2: $100 - $100 = $0. Unit total $300.
+    ma_tafdc_partially_disregarded_earned_income: [300, 0, 0]
+
+- name: Two earners with two children below the cap, the higher earner pays
+  period: 2026-01
+  input:
+    people:
+      parent1:
+        age: 30
+        employment_income_before_lsr: 12_000  # $1,000/month
+        weekly_hours_worked_before_lsr: 40
+      parent2:
+        age: 30
+        employment_income_before_lsr: 4_800  # $400/month
+        weekly_hours_worked_before_lsr: 40
+      child1:
+        age: 1
+      child2:
+        age: 5
+    tax_units:
+      tax_unit1:
+        members: [parent1, child1, child2]
+      tax_unit2:
+        members: [parent2]
+    spm_units:
+      spm_unit:
+        members: [parent1, parent2, child1, child2]
+        is_tanf_enrolled: true
+        spm_unit_pre_subsidy_childcare_expenses: 4_200
+    households:
+      household:
+        members: [parent1, parent2, child1, child2]
+        state_code: MA
+  output:
+    # Care is $4,200 / 12 = $350 a month, $175 for each child. Child age 1:
+    # min($200, $175) = $175; child age 5: min($175, $175) = $175; total $350.
+    ma_tafdc_dependent_care_deduction: 350
+    # parent1: ($1,000 - $200) x 0.5 = $400; parent2: ($400 - $200) x 0.5 = $100.
+    # parent1 pays: $400 - $350 = $50; parent2 keeps $100. Unit total $150.
+    # Before, each earner had the full $350 subtracted: $50 and $0.
+    ma_tafdc_partially_disregarded_earned_income: [50, 100, 0, 0]
+
+- name: Two earners whose earnings after the disregard are below the deduction
+  period: 2026-01
+  input:
+    people:
+      parent1:
+        age: 30
+        employment_income_before_lsr: 3_600  # $300/month
+        weekly_hours_worked_before_lsr: 40
+      parent2:
+        age: 30
+        employment_income_before_lsr: 3_600  # $300/month
+        weekly_hours_worked_before_lsr: 40
+      child:
+        age: 1
+    tax_units:
+      tax_unit1:
+        members: [parent1, child]
+      tax_unit2:
+        members: [parent2]
+    spm_units:
+      spm_unit:
+        members: [parent1, parent2, child]
+        is_tanf_enrolled: true
+        spm_unit_pre_subsidy_childcare_expenses: 3_000
+    households:
+      household:
+        members: [parent1, parent2, child]
+        state_code: MA
+  output:
+    ma_tafdc_dependent_care_deduction: 200
+    # Each: ($300 - $200) x 0.5 = $50. parent1 pays (first of two equal
+    # earners): max($50 - $200, 0) = $0. The other $150 of the deduction does
+    # not reduce parent2's earnings: parent2 keeps $50. Unit total $50.
+    ma_tafdc_partially_disregarded_earned_income: [0, 50, 0]
+
+- name: Single parent with one child, unchanged
+  period: 2026-01
+  input:
+    people:
+      parent:
+        age: 30
+        employment_income_before_lsr: 12_000  # $1,000/month
+        weekly_hours_worked_before_lsr: 40
+      child:
+        age: 1
+    tax_units:
+      tax_unit:
+        members: [parent, child]
+    spm_units:
+      spm_unit:
+        members: [parent, child]
+        is_tanf_enrolled: true
+        spm_unit_pre_subsidy_childcare_expenses: 3_000
+    households:
+      household:
+        members: [parent, child]
+        state_code: MA
+  output:
+    # ($1,000 - $200) x 0.5 = $400; $400 - $200 = $200.
+    ma_tafdc_partially_disregarded_earned_income: [200, 0]
+
+- name: One earner on a joint return, annual grant
+  period: 2026
+  input:
+    people:
+      parent1:
+        age: 30
+        employment_income_before_lsr: 12_000
+        weekly_hours_worked_before_lsr: 40
+      parent2:
+        age: 30
+      child:
+        age: 1
+    tax_units:
+      tax_unit:
+        members: [parent1, parent2, child]
+    marital_units:
+      marital_unit:
+        members: [parent1, parent2]
+    spm_units:
+      spm_unit:
+        members: [parent1, parent2, child]
+        is_tanf_enrolled: true
+        spm_unit_pre_subsidy_childcare_expenses: 3_000
+    households:
+      household:
+        members: [parent1, parent2, child]
+        state_code: MA
+  output:
+    # $200 a month after the deductions, counted for the 6 months after the
+    # six-month 100% disregard: $200 x 6 = $1,200.
+    ma_tafdc_countable_earned_income: [1_200, 0, 0]
+    # Payment standard $901 x 12 = $10,812; ($901 - $1,200 / 12) x 12 = $9,612,
+    # plus the $500 clothing allowance for the child.
+    ma_tafdc: 10_112
+
+- name: Two equal earners on separate returns, annual grant
+  period: 2026
+  input:
+    people:
+      parent1:
+        age: 30
+        employment_income_before_lsr: 8_400
+        weekly_hours_worked_before_lsr: 40
+      parent2:
+        age: 30
+        employment_income_before_lsr: 8_400
+        weekly_hours_worked_before_lsr: 40
+      child:
+        age: 1
+    tax_units:
+      tax_unit1:
+        members: [parent1, child]
+      tax_unit2:
+        members: [parent2]
+    spm_units:
+      spm_unit:
+        members: [parent1, parent2, child]
+        is_tanf_enrolled: true
+        spm_unit_pre_subsidy_childcare_expenses: 3_000
+    households:
+      household:
+        members: [parent1, parent2, child]
+        state_code: MA
+  output:
+    # $50 (payer) and $250 a month for the 6 months after the 100% disregard:
+    # $300 and $1,500.
+    ma_tafdc_countable_earned_income: [300, 1_500, 0]
+    # ($901 - $1,800 / 12) x 12 = $9,012, plus the $500 clothing allowance.
+    ma_tafdc: 9_512
+
+- name: Two unequal earners, the lower earner pays, annual grant
+  period: 2026
+  input:
+    people:
+      parent1:
+        age: 30
+        employment_income_before_lsr: 12_000
+        weekly_hours_worked_before_lsr: 40
+        ma_tafdc_dependent_care_payer: false
+      parent2:
+        age: 30
+        employment_income_before_lsr: 4_800
+        weekly_hours_worked_before_lsr: 40
+        ma_tafdc_dependent_care_payer: true
+      child:
+        age: 1
+        ma_tafdc_dependent_care_payer: false
+    tax_units:
+      tax_unit1:
+        members: [parent1, child]
+      tax_unit2:
+        members: [parent2]
+    spm_units:
+      spm_unit:
+        members: [parent1, parent2, child]
+        is_tanf_enrolled: true
+        spm_unit_pre_subsidy_childcare_expenses: 3_000
+    households:
+      household:
+        members: [parent1, parent2, child]
+        state_code: MA
+  output:
+    # $400 and $0 a month for the 6 months after the 100% disregard:
+    # $2,400 and $0.
+    ma_tafdc_countable_earned_income: [2_400, 0, 0]
+    # ($901 - $2,400 / 12) x 12 = $8,412, plus the $500 clothing allowance.
+    ma_tafdc: 8_912
diff --git a/policyengine_us/variables/gov/states/ma/dta/tcap/tafdc/income/deductions/ma_tafdc_dependent_care_payer.py b/policyengine_us/variables/gov/states/ma/dta/tcap/tafdc/income/deductions/ma_tafdc_dependent_care_payer.py
new file mode 100644
index 00000000000..1fc7113dcd4
--- /dev/null
+++ b/policyengine_us/variables/gov/states/ma/dta/tcap/tafdc/income/deductions/ma_tafdc_dependent_care_payer.py
@@ -0,0 +1,26 @@
+from policyengine_us.model_api import *
+
+
+class ma_tafdc_dependent_care_payer(Variable):
+    value_type = bool
+    entity = Person
+    label = "Pays the dependent care expenses for the Massachusetts Temporary Assistance for Families with Dependent Children (TAFDC) dependent care deduction"
+    definition_period = YEAR
+    reference = (
+        "https://www.law.cornell.edu/regulations/massachusetts/106-CMR-704-275",  # (A)
+        "https://eohhs.ehs.state.ma.us/DTA/PolicyOnline/BEACON5/%21SSL%21/WebHelp/TAFDC/Employment/Emp_DepCareExTAFDC.htm",
+    )
+    defined_for = StateCode.MA
+
+    def formula(person, period, parameters):
+        # Per 106 CMR 704.275(A), an employed applicant or client receives
+        # the deduction for the expenditure on care, and DTA's BEACON help
+        # applies it as a deduction for the client incurring the expense.
+        # The SPM unit's care expenses do not record who pays them, so the
+        # payer is the head or spouse with the highest gross earnings (the
+        # first such member when earnings are equal). Set this variable to
+        # name the member who pays.
+        head_or_spouse = person("is_tax_unit_head_or_spouse", period)
+        earnings = person("ma_tcap_gross_earned_income", period)
+        rank = person.get_rank(person.spm_unit, -earnings, head_or_spouse)
+        return rank == 0
diff --git a/policyengine_us/variables/gov/states/ma/dta/tcap/tafdc/income/earned/ma_tafdc_partially_disregarded_earned_income.py b/policyengine_us/variables/gov/states/ma/dta/tcap/tafdc/income/earned/ma_tafdc_partially_disregarded_earned_income.py
index 2518a4ce3a1..332b205087d 100644
--- a/policyengine_us/variables/gov/states/ma/dta/tcap/tafdc/income/earned/ma_tafdc_partially_disregarded_earned_income.py
+++ b/policyengine_us/variables/gov/states/ma/dta/tcap/tafdc/income/earned/ma_tafdc_partially_disregarded_earned_income.py
@@ -7,7 +7,12 @@ class ma_tafdc_partially_disregarded_earned_income(Variable):
     entity = Person
     label = "Massachusetts Temporary Assistance for Families with Dependent Children (TAFDC) partially disregarded earned income"
     definition_period = MONTH
-    reference = "https://www.law.cornell.edu/regulations/massachusetts/106-CMR-704-281"
+    reference = (
+        "https://www.law.cornell.edu/regulations/massachusetts/106-CMR-704-281",
+        "https://www.law.cornell.edu/regulations/massachusetts/106-CMR-704-275",  # (A)
+        "https://www.law.cornell.edu/regulations/massachusetts/106-CMR-704-500",  # (A)
+        "https://eohhs.ehs.state.ma.us/DTA/PolicyOnline/BEACON5/%21SSL%21/WebHelp/TAFDC/Employment/Emp_DepCareExTAFDC.htm",
+    )
     defined_for = StateCode.MA
 
     def formula(person, period, parameters):
@@ -20,17 +25,30 @@ def formula(person, period, parameters):
         earned_income_after_work_related_deduction = max_(
             0, gross_earned_income - work_related_deduction
         )
-        filing_status = person.tax_unit("filing_status", period)
-        joint = filing_status == filing_status.possible_values.JOINT
+        earned_income_after_disregard = (
+            earned_income_after_work_related_deduction * p.percentage
+        )
+        # Per 106 CMR 704.275(A), the dependent care deduction is made after the
+        # 50% disregard, and an employed applicant or client receives it for
+        # the expenditure on care. 106 CMR 704.500(A) Steps 2-4 apply the work
+        # expense and the 50% disregard to each member, then the dependent
+        # care deduction, then total the members' countable earned income.
+        # The unit's deduction is subtracted once, from the earnings of the
+        # member who pays for the care. A part of the deduction above that
+        # member's earnings does not reduce another member's earnings. If more
+        # than one member is set as a payer, they share the deduction equally.
         dependent_care_deduction = person.spm_unit(
             "ma_tafdc_dependent_care_deduction", period
         )
-        # Attributing the dependent care deduction equally to each spouse if filing jointly
-        applicable_dependent_care_deduction = where(
-            joint, dependent_care_deduction / 2, dependent_care_deduction
+        payer = person("ma_tafdc_dependent_care_payer", period.this_year)
+        payer_count = person.spm_unit.sum(payer)
+        share = np.divide(
+            payer.astype(float),
+            payer_count,
+            out=np.zeros_like(earned_income_after_disregard, dtype=float),
+            where=payer_count > 0,
         )
         return max_(
             0,
-            earned_income_after_work_related_deduction * p.percentage
-            - applicable_dependent_care_deduction,
+            earned_income_after_disregard - dependent_care_deduction * share,
         )