diff --git a/changelog.d/backdate-federal-tanf-income-sources.changed.md b/changelog.d/backdate-federal-tanf-income-sources.changed.md
new file mode 100644
index 00000000000..c27fd47b2d6
--- /dev/null
+++ b/changelog.d/backdate-federal-tanf-income-sources.changed.md
@@ -0,0 +1 @@
+Backdate federal TANF earned and unearned income source parameters to 1997-07-01.
diff --git a/changelog.d/backdate-in-tanf.added.md b/changelog.d/backdate-in-tanf.added.md
new file mode 100644
index 00000000000..6289b704d6f
--- /dev/null
+++ b/changelog.d/backdate-in-tanf.added.md
@@ -0,0 +1 @@
+Backdate Indiana TANF parameters to 1997 program inception. Differentiate applicant vs. recipient income deductions with 4-month earned income disregard limit.
diff --git a/policyengine_us/parameters/gov/states/in/fssa/tanf/eligibility/continuing/fpg_rate.yaml b/policyengine_us/parameters/gov/states/in/fssa/tanf/eligibility/continuing/fpg_rate.yaml
index d567c1b88c6..2c6d1d3aeaf 100644
--- a/policyengine_us/parameters/gov/states/in/fssa/tanf/eligibility/continuing/fpg_rate.yaml
+++ b/policyengine_us/parameters/gov/states/in/fssa/tanf/eligibility/continuing/fpg_rate.yaml
@@ -1,12 +1,14 @@
 description: Indiana uses this multiplier of the federal poverty guideline for continuing eligibility under the Temporary Assistance for Needy Families program.
 
 values:
-  2023-07-01: 1
+  1997-10-01: 1
 
 metadata:
   unit: /1
   period: month
   label: Indiana TANF continuing eligibility FPG rate
   reference:
-    - title: 470 IAC 10.3-4-1
+    - title: 470 IAC 10.3-4-1 (net income at or below 100% FPG)
       href: https://iar.iga.in.gov/code/2026/470/10.3#470-10.3-4-1
+    - title: FSSA DFR Chapter 3000, Section 3010.15.05 (100% FPG continuing eligibility)
+      href: https://www.in.gov/fssa/dfr/files/3000.pdf#page=5
diff --git a/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/benefit/earned_income_disregard/rate.yaml b/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/benefit/earned_income_disregard/rate.yaml
index 46cd8cb4c89..3cc6ecdef90 100644
--- a/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/benefit/earned_income_disregard/rate.yaml
+++ b/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/benefit/earned_income_disregard/rate.yaml
@@ -1,7 +1,7 @@
 description: Indiana excludes this share of earned income when calculating benefits under the Temporary Assistance for Needy Families program.
 
 values:
-  2023-07-01: 0.75
+  1997-10-01: 0.75
 
 metadata:
   unit: /1
@@ -10,3 +10,5 @@ metadata:
   reference:
     - title: 470 IAC 10.3-4-4(d)(1)
       href: https://iar.iga.in.gov/code/2026/470/10.3#470-10.3-4-4
+    - title: FSSA DFR Chapter 3400, Section 3450.35.05 (75% earned income disregard)
+      href: https://www.in.gov/fssa/dfr/files/3400.pdf#page=41
diff --git a/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/eligibility/earned_income_disregard/months.yaml b/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/eligibility/earned_income_disregard/months.yaml
new file mode 100644
index 00000000000..7f2dd6b73ba
--- /dev/null
+++ b/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/eligibility/earned_income_disregard/months.yaml
@@ -0,0 +1,14 @@
+description: Indiana applies the earned income disregard for this number of months under the Temporary Assistance for Needy Families program.
+
+values:
+  1997-10-01: 4
+
+metadata:
+  unit: month
+  period: month
+  label: Indiana TANF eligibility earned income disregard months
+  reference:
+    - title: 470 IAC 10.3-4-4(c)(2)
+      href: https://iar.iga.in.gov/code/2026/470/10.3#470-10.3-4-4
+    - title: FSSA DFR Chapter 3400, Section 3450.25.00 ($30 and 1/3 disregard)
+      href: https://www.in.gov/fssa/dfr/files/3400.pdf#page=38
diff --git a/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/eligibility/earned_income_disregard/rate.yaml b/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/eligibility/earned_income_disregard/rate.yaml
index ed09c6ed7da..626c7bc21ef 100644
--- a/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/eligibility/earned_income_disregard/rate.yaml
+++ b/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/eligibility/earned_income_disregard/rate.yaml
@@ -1,7 +1,7 @@
 description: Indiana excludes this share of earned income when determining eligibility under the Temporary Assistance for Needy Families program.
 
 values:
-  2023-07-01: 0.33
+  1997-10-01: 0.33
 
 metadata:
   unit: /1
@@ -10,3 +10,5 @@ metadata:
   reference:
     - title: 470 IAC 10.3-4-4(c)(2)
       href: https://iar.iga.in.gov/code/2026/470/10.3#470-10.3-4-4
+    - title: FSSA DFR Chapter 3400, Section 3450.25.00 ($30 and 1/3 disregard)
+      href: https://www.in.gov/fssa/dfr/files/3400.pdf#page=38
diff --git a/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/eligibility/flat_disregard/amount.yaml b/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/eligibility/flat_disregard/amount.yaml
index 202290bbaca..bb5114e7789 100644
--- a/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/eligibility/flat_disregard/amount.yaml
+++ b/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/eligibility/flat_disregard/amount.yaml
@@ -1,7 +1,7 @@
 description: Indiana deducts this amount from earned income when determining eligibility under the Temporary Assistance for Needy Families program.
 
 values:
-  2023-07-01: 30
+  1997-10-01: 30
 
 metadata:
   unit: currency-USD
@@ -10,3 +10,5 @@ metadata:
   reference:
     - title: 470 IAC 10.3-4-4(c)(2)
       href: https://iar.iga.in.gov/code/2026/470/10.3#470-10.3-4-4
+    - title: FSSA DFR Chapter 3400, Section 3450.25.00 ($30 and 1/3 disregard)
+      href: https://www.in.gov/fssa/dfr/files/3400.pdf#page=38
diff --git a/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/work_expense/amount.yaml b/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/work_expense/amount.yaml
index a917a2db707..b3478490ccc 100644
--- a/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/work_expense/amount.yaml
+++ b/policyengine_us/parameters/gov/states/in/fssa/tanf/income/deductions/work_expense/amount.yaml
@@ -1,7 +1,7 @@
 description: Indiana deducts this amount from gross earned income as work-related expenses under the Temporary Assistance for Needy Families program.
 
 values:
-  2023-07-01: 90
+  1997-10-01: 90
 
 metadata:
   unit: currency-USD
@@ -10,3 +10,5 @@ metadata:
   reference:
     - title: 470 IAC 10.3-4-4(c)(1)
       href: https://iar.iga.in.gov/code/2026/470/10.3#470-10.3-4-4
+    - title: FSSA DFR Chapter 3400, Section 3450.20.00 ($90 work expense disregard)
+      href: https://www.in.gov/fssa/dfr/files/3400.pdf#page=38
diff --git a/policyengine_us/parameters/gov/states/in/fssa/tanf/resources/limit/at_application/amount.yaml b/policyengine_us/parameters/gov/states/in/fssa/tanf/resources/limit/at_application/amount.yaml
index 72170a781a0..5d3c0ee30a5 100644
--- a/policyengine_us/parameters/gov/states/in/fssa/tanf/resources/limit/at_application/amount.yaml
+++ b/policyengine_us/parameters/gov/states/in/fssa/tanf/resources/limit/at_application/amount.yaml
@@ -1,12 +1,14 @@
 description: Indiana limits resources to this amount when applying for the Temporary Assistance for Needy Families program.
 
 values:
-  2023-07-01: 1_000
+  1997-10-01: 1_000
 
 metadata:
   unit: currency-USD
   period: month
   label: Indiana TANF resource limit at application amount
   reference:
-    - title: 470 IAC 10.3-4-2
+    - title: 470 IAC 10.3-4-2(1)
       href: https://iar.iga.in.gov/code/2026/470/10.3#470-10.3-4-2
+    - title: FSSA DFR Chapter 3000, Section 3005.10.00 (resource limits)
+      href: https://www.in.gov/fssa/dfr/files/3000.pdf#page=2
diff --git a/policyengine_us/parameters/gov/states/in/fssa/tanf/resources/limit/while_receiving/amount.yaml b/policyengine_us/parameters/gov/states/in/fssa/tanf/resources/limit/while_receiving/amount.yaml
index 72a58354fe9..2040275ab2a 100644
--- a/policyengine_us/parameters/gov/states/in/fssa/tanf/resources/limit/while_receiving/amount.yaml
+++ b/policyengine_us/parameters/gov/states/in/fssa/tanf/resources/limit/while_receiving/amount.yaml
@@ -1,12 +1,17 @@
 description: Indiana limits resources to this amount while receiving the Temporary Assistance for Needy Families program.
 
 values:
-  2023-07-01: 10_000
+  1997-10-01: 1_500
+  2022-07-01: 10_000
 
 metadata:
   unit: currency-USD
   period: month
   label: Indiana TANF resource limit while receiving amount
   reference:
-    - title: IC 12-14-1-1(b)
+    - title: IC 12-14-1-1(b), as amended by P.L.83-2022, SEC.2
       href: https://iga.in.gov/laws/2025/ic/titles/12/#12-14-1-1
+    - title: FSSA DFR Chapter 3000, Section 3005.10.00 (resource limits effective 7/1/2022)
+      href: https://www.in.gov/fssa/dfr/files/3000.pdf#page=2
+    - title: Urban Institute Welfare Rules Database, Table L8 ($1,500 recipient limit as of July 1998)
+      href: https://wrd.urban.org/sites/default/files/documents/2023-09/311111-The-Welfare-Rules-Databook-State-Policies-as-of-July--.PDF#page=160
diff --git a/policyengine_us/parameters/gov/states/in/fssa/tanf/resources/vehicle_exemption/amount.yaml b/policyengine_us/parameters/gov/states/in/fssa/tanf/resources/vehicle_exemption/amount.yaml
index d455bcbcd2d..58b483fcd3d 100644
--- a/policyengine_us/parameters/gov/states/in/fssa/tanf/resources/vehicle_exemption/amount.yaml
+++ b/policyengine_us/parameters/gov/states/in/fssa/tanf/resources/vehicle_exemption/amount.yaml
@@ -1,7 +1,10 @@
 description: Indiana excludes this amount of vehicle equity from countable resources under the Temporary Assistance for Needy Families program.
 
 values:
-  2023-07-01: 20_000
+  1997-10-01: 1_000
+  1999-07-01: 5_000
+  2021-07-01: 10_000
+  2022-07-01: 20_000
 
 metadata:
   unit: currency-USD
@@ -10,3 +13,7 @@ metadata:
   reference:
     - title: IC 12-14-2-1(b)(2)
       href: https://iga.in.gov/laws/2025/ic/titles/12/#12-14-2-1
+    - title: FSSA DFR Chapter 2600, Section 2615.60.15 ($10,000 until 6/30/2022, $20,000 effective 7/1/2022)
+      href: https://www.in.gov/fssa/dfr/files/2600.pdf#page=30
+    - title: Urban Institute Welfare Rules Database, Table L9 ($1,000 at inception, $5,000 from July 1999, $10,000 from July 2021)
+      href: https://wrd.urban.org/welfare-rules-databook
diff --git a/policyengine_us/parameters/gov/states/in/fssa/tanf/standard_of_need/amount.yaml b/policyengine_us/parameters/gov/states/in/fssa/tanf/standard_of_need/amount.yaml
index 41e71620a2b..bfab15af01f 100644
--- a/policyengine_us/parameters/gov/states/in/fssa/tanf/standard_of_need/amount.yaml
+++ b/policyengine_us/parameters/gov/states/in/fssa/tanf/standard_of_need/amount.yaml
@@ -1,24 +1,34 @@
 description: Indiana provides this amount as the standard of need under the Temporary Assistance for Needy Families program.
 
 1:
+  1997-10-01: 139
   2023-07-01: 155
 2:
+  1997-10-01: 229
   2023-07-01: 255
 3:
+  1997-10-01: 288
   2023-07-01: 320
 4:
+  1997-10-01: 346
   2023-07-01: 385
 5:
+  1997-10-01: 405
   2023-07-01: 450
 6:
+  1997-10-01: 463
   2023-07-01: 515
 7:
+  1997-10-01: 522
   2023-07-01: 580
 8:
+  1997-10-01: 580
   2023-07-01: 645
 9:
+  1997-10-01: 639
   2023-07-01: 710
 10:
+  1997-10-01: 697
   2023-07-01: 775
 
 metadata:
@@ -27,10 +37,12 @@ metadata:
   breakdown:
     - range(1, 11)
   breakdown_labels:
-    - Household size
+    - Assistance unit size
   label: Indiana TANF standard of need amount
   reference:
     - title: 470 IAC 10.3-4-3(a)(1)
       href: https://iar.iga.in.gov/code/2026/470/10.3#470-10.3-4-3
-    - title: IC 12-14-2-5
+    - title: IC 12-14-2-5 (amount of assistance; standard of need)
       href: https://iga.in.gov/laws/2025/ic/titles/12/#12-14-2-5
+    - title: Indiana DCS Unlicensed Relative Placements, Table 3 (corroborates pre-2023 standard of need values)
+      href: https://www.in.gov/dcs/files/16.2%20Assistance%20for%20Unlicensed%20Relative%20Placements.pdf#page=7
diff --git a/policyengine_us/parameters/gov/states/in/fssa/tanf/standard_of_need/max_unit_size.yaml b/policyengine_us/parameters/gov/states/in/fssa/tanf/standard_of_need/max_unit_size.yaml
index ba29895fdb6..267136bd61e 100644
--- a/policyengine_us/parameters/gov/states/in/fssa/tanf/standard_of_need/max_unit_size.yaml
+++ b/policyengine_us/parameters/gov/states/in/fssa/tanf/standard_of_need/max_unit_size.yaml
@@ -1,12 +1,12 @@
 description: Indiana sets this as the maximum unit size for standard of need lookup under the Temporary Assistance for Needy Families program.
 
 values:
-  2023-07-01: 10
+  1997-10-01: 10
 
 metadata:
   unit: person
   period: year
   label: Indiana TANF standard of need max unit size
   reference:
-    - title: 470 IAC 10.3-4-3
+    - title: 470 IAC 10.3-4-3(a)(1)
       href: https://iar.iga.in.gov/code/2026/470/10.3#470-10.3-4-3
diff --git a/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/benefit/in_tanf_payment_standard.yaml b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/benefit/in_tanf_payment_standard.yaml
index 93c2c7a849f..05a56b20385 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/benefit/in_tanf_payment_standard.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/benefit/in_tanf_payment_standard.yaml
@@ -49,6 +49,30 @@
   output:
     in_tanf_payment_standard: 515
 
+- name: Payment standard for family of 7
+  period: 2024-01
+  input:
+    spm_unit_size: 7
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 580
+
+- name: Payment standard for family of 8
+  period: 2024-01
+  input:
+    spm_unit_size: 8
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 645
+
+- name: Payment standard for family of 9
+  period: 2024-01
+  input:
+    spm_unit_size: 9
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 710
+
 - name: Payment standard for family of 10
   period: 2024-01
   input:
diff --git a/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/benefit/in_tanf_payment_standard_historical.yaml b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/benefit/in_tanf_payment_standard_historical.yaml
new file mode 100644
index 00000000000..eeea1318130
--- /dev/null
+++ b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/benefit/in_tanf_payment_standard_historical.yaml
@@ -0,0 +1,108 @@
+# Historical payment standard tests (pre-SEA 265 era)
+# Benefits were frozen at 1988 AFDC levels from 1997-10-01 through 2023-06-30
+
+- name: Pre-reform payment standard for family of 1
+  period: 2020-01
+  input:
+    spm_unit_size: 1
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 139
+
+- name: Pre-reform payment standard for family of 2
+  period: 2020-01
+  input:
+    spm_unit_size: 2
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 229
+
+- name: Pre-reform payment standard for family of 3
+  period: 2020-01
+  input:
+    spm_unit_size: 3
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 288
+
+- name: Pre-reform payment standard for family of 4
+  period: 2020-01
+  input:
+    spm_unit_size: 4
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 346
+
+- name: Pre-reform payment standard for family of 5
+  period: 2020-01
+  input:
+    spm_unit_size: 5
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 405
+
+- name: Pre-reform payment standard for family of 6
+  period: 2020-01
+  input:
+    spm_unit_size: 6
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 463
+
+- name: Pre-reform payment standard for family of 7
+  period: 2020-01
+  input:
+    spm_unit_size: 7
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 522
+
+- name: Pre-reform payment standard for family of 8
+  period: 2020-01
+  input:
+    spm_unit_size: 8
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 580
+
+- name: Pre-reform payment standard for family of 9
+  period: 2020-01
+  input:
+    spm_unit_size: 9
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 639
+
+- name: Pre-reform payment standard for family of 10
+  period: 2020-01
+  input:
+    spm_unit_size: 10
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 697
+
+# Transition boundary tests
+
+- name: Pre-reform January 2023 still uses old values
+  period: 2023-01
+  input:
+    spm_unit_size: 3
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 288
+
+- name: Post-reform January 2024 uses new values
+  period: 2024-01
+  input:
+    spm_unit_size: 3
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 320
+
+- name: Pre-reform era at program inception (1998)
+  period: 1998-01
+  input:
+    spm_unit_size: 3
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 288
diff --git a/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/edge_cases.yaml b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/edge_cases.yaml
new file mode 100644
index 00000000000..d3a36661274
--- /dev/null
+++ b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/edge_cases.yaml
@@ -0,0 +1,145 @@
+# Indiana TANF edge case tests
+
+# Edge case: Earner at exactly $90 (work expense disregard boundary)
+- name: Earner at exactly $90 - all income disregarded for eligibility
+  period: 2024-01
+  input:
+    people:
+      person1:
+        tanf_gross_earned_income: 90
+      person2:
+        age: 10
+    spm_units:
+      spm_unit:
+        members: [person1, person2]
+    households:
+      household:
+        members: [person1, person2]
+        state_code: IN
+  output:
+    in_tanf_countable_earned_income_for_eligibility: [0, 0]
+    # Applicant (not enrolled): $90 - $90 = $0
+    in_tanf_countable_earned_income: [22.5, 22.5]
+    # $90 * 0.25 = $22.50
+
+# Edge case: Earner at exactly $120 ($90 + $30 disregard boundary)
+- name: Earner at exactly $120 - flat disregard exactly zeros remainder
+  period: 2024-01
+  input:
+    people:
+      person1:
+        tanf_gross_earned_income: 120
+      person2:
+        age: 10
+    spm_units:
+      spm_unit:
+        members: [person1, person2]
+        is_tanf_enrolled: true
+    households:
+      household:
+        members: [person1, person2]
+        state_code: IN
+  output:
+    in_tanf_countable_earned_income_for_eligibility: [0, 0]
+    # $120 - $90 = $30; $30 - $30 = $0; $0 * 0.67 = $0
+
+# Edge case: Family of 8 (max pre-reform) vs family of 9
+- name: Family of 8 gets size-8 standard pre-reform
+  period: 2020-01
+  input:
+    spm_unit_size: 8
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 580
+
+- name: Family of 9 gets size-9 standard pre-reform
+  period: 2020-01
+  input:
+    spm_unit_size: 9
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 639
+
+# Edge case: Family of 10 post-reform gets size-10 value
+- name: Family of 10 gets size-10 standard post-reform
+  period: 2024-01
+  input:
+    spm_unit_size: 10
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 775
+
+# Edge case: Family of 12 capped at max unit size post-reform
+- name: Family of 12 capped at size-10 post-reform
+  period: 2024-01
+  input:
+    spm_unit_size: 12
+    state_code: IN
+  output:
+    in_tanf_payment_standard: 775
+
+# Edge case: Income just below eligibility threshold
+- name: Income just below standard of need threshold
+  period: 2024-01
+  input:
+    in_tanf_countable_income_for_eligibility: 319
+    in_tanf_payment_standard: 320
+    is_tanf_enrolled: false
+    state_code: IN
+  output:
+    in_tanf_countable_income_eligible: true
+    # $319 < $320 = true
+
+# Edge case: Income at exactly the threshold
+- name: Income at exactly standard of need threshold
+  period: 2024-01
+  input:
+    in_tanf_countable_income_for_eligibility: 320
+    in_tanf_payment_standard: 320
+    is_tanf_enrolled: false
+    state_code: IN
+  output:
+    in_tanf_countable_income_eligible: false
+    # $320 < $320 = false (strict less-than)
+
+# Edge case: Resources at exactly the application limit
+- name: Resources at exactly $1,000 application limit
+  period: 2024-01
+  input:
+    state_code: IN
+    in_tanf_countable_resources: 1_000
+    is_tanf_enrolled: false
+  output:
+    in_tanf_resources_eligible: true
+    # $1,000 <= $1,000 = true
+
+# Edge case: Resources $1 over application limit
+- name: Resources $1 over application limit
+  period: 2024-01
+  input:
+    state_code: IN
+    in_tanf_countable_resources: 1_001
+    is_tanf_enrolled: false
+  output:
+    in_tanf_resources_eligible: false
+
+# Edge case: Resources at exactly enrolled limit
+- name: Resources at exactly $10,000 enrolled limit
+  period: 2024-01
+  input:
+    state_code: IN
+    in_tanf_countable_resources: 10_000
+    is_tanf_enrolled: true
+  output:
+    in_tanf_resources_eligible: true
+
+# Edge case: Benefit equals exactly $1 (near-zero benefit)
+- name: Benefit of exactly $1
+  period: 2024-01
+  input:
+    in_tanf_eligible: true
+    in_tanf_payment_standard: 320
+    in_tanf_countable_income_for_payment: 319
+    state_code: IN
+  output:
+    in_tanf: 1
diff --git a/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/eligibility/in_tanf_countable_income_eligible.yaml b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/eligibility/in_tanf_countable_income_eligible.yaml
index 8b51f3580fb..1981c761495 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/eligibility/in_tanf_countable_income_eligible.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/eligibility/in_tanf_countable_income_eligible.yaml
@@ -1,5 +1,5 @@
 # Tests for in_tanf_countable_income_eligible
-# Uses eligibility disregards: $90/earner, $30/unit, 1/3 of remainder
+# Uses eligibility disregards: $90/earner, $30/earner, 1/3 of remainder
 # Compares to standard of need (initial) or FPL (continuing)
 
 - name: Family of 3 with zero income - eligible
@@ -39,6 +39,7 @@
     spm_units:
       spm_unit:
         members: [person1, person2, person3]
+        is_tanf_enrolled: true
     households:
       household:
         members: [person1, person2, person3]
@@ -46,13 +47,13 @@
   output:
     in_tanf_countable_earned_income_for_eligibility: [120.6, 120.6, 120.6]
     # $300 - $90 (work expense) = $210
-    # $210 - $30 (unit disregard) = $180
+    # $210 - $30 (flat disregard) = $180
     # $180 * (1 - 0.33) = $120.60
     in_tanf_countable_income_for_eligibility: [120.6, 120.6, 120.6]
     in_tanf_countable_income_eligible: [true, true, true]
-    # Countable ($120.60) < standard of need ($320) → eligible
+    # Enrolled: countable ($120.60) < 100% FPL for 3 → eligible
 
-- name: Family of 3 with moderate earned income - not eligible
+- name: Applicant family of 3 with moderate earned income - not eligible
   period: 2024-01
   input:
     people:
@@ -66,18 +67,17 @@
     spm_units:
       spm_unit:
         members: [person1, person2, person3]
+        is_tanf_enrolled: false
     households:
       household:
         members: [person1, person2, person3]
         state_code: IN
   output:
-    in_tanf_countable_earned_income_for_eligibility: [321.6, 321.6, 321.6]
-    # $600 - $90 = $510
-    # $510 - $30 = $480
-    # $480 * 0.67 = $321.60
-    in_tanf_countable_income_for_eligibility: [321.6, 321.6, 321.6]
+    in_tanf_countable_earned_income_for_eligibility: [510, 510, 510]
+    # Applicant: $600 - $90 = $510 ($90 work expense only)
+    in_tanf_countable_income_for_eligibility: [510, 510, 510]
     in_tanf_countable_income_eligible: [false, false, false]
-    # Countable ($321.60) >= standard of need ($320) → not eligible
+    # Applicant threshold = standard of need ($320); $510 >= $320 → not eligible
 
 - name: Family of 2 with earned income at threshold - not eligible
   period: 2024-01
@@ -91,6 +91,7 @@
     spm_units:
       spm_unit:
         members: [person1, person2]
+        is_tanf_enrolled: true
     households:
       household:
         members: [person1, person2]
@@ -102,7 +103,7 @@
     # $380 * 0.67 = $254.60
     in_tanf_countable_income_for_eligibility: [254.6, 254.6]
     in_tanf_countable_income_eligible: [true, true]
-    # Countable ($254.60) < standard of need ($255) → eligible
+    # Enrolled: countable ($254.60) < 100% FPL for 2 → eligible
 
 - name: Two earners - each gets $90 disregard
   period: 2024-01
@@ -119,20 +120,18 @@
     spm_units:
       spm_unit:
         members: [person1, person2, person3]
+        is_tanf_enrolled: true
     households:
       household:
         members: [person1, person2, person3]
         state_code: IN
   output:
-    in_tanf_countable_earned_income_for_eligibility: [127.3, 127.3, 127.3]
-    # Person1: $200 - $90 = $110
-    # Person2: $200 - $90 = $110
-    # Unit total: $220
-    # $220 - $30 = $190
-    # $190 * 0.67 = $127.30
-    in_tanf_countable_income_for_eligibility: [127.3, 127.3, 127.3]
+    in_tanf_countable_earned_income_for_eligibility: [107.2, 107.2, 107.2]
+    # Per earner: ($200-$90-$30)*0.67 = $80*0.67 = $53.60
+    # Unit total: $53.60 + $53.60 = $107.20
+    in_tanf_countable_income_for_eligibility: [107.2, 107.2, 107.2]
     in_tanf_countable_income_eligible: [true, true, true]
-    # Countable ($127.30) < standard of need ($320) → eligible
+    # Enrolled: countable ($107.20) < 100% FPL for 3 → eligible
 
 - name: Continuing eligibility uses FPL threshold
   period: 2024-01
diff --git a/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/income/in_tanf_countable_earned_income_for_eligibility.yaml b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/income/in_tanf_countable_earned_income_for_eligibility.yaml
index df24ab0de97..5e48502169a 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/income/in_tanf_countable_earned_income_for_eligibility.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/income/in_tanf_countable_earned_income_for_eligibility.yaml
@@ -1,58 +1,62 @@
 # Tests for in_tanf_countable_earned_income_for_eligibility
-# Applies: $90/earner (per person), then $30 + 1/3 per unit
+# Enrolled (months 1-4): $90/earner + $30 flat + 1/3 disregard
+# Enrolled (months 5-12): $90/earner + $30 flat only
+# Applicant (not enrolled): $90/earner only
 
-- name: Family of 3 with 1 earner - gets $90 work expense disregard
+# --- Continuing recipients (enrolled, January = month 1, phase 1) ---
+
+- name: Case 1, enrolled family of 3 with 1 earner.
   period: 2024-01
+  absolute_error_margin: 0.1
   input:
     people:
-      parent1:
+      person1:
         tanf_gross_earned_income: 400
-      parent2:
+      person2:
         tanf_gross_earned_income: 0
-      child:
+      person3:
         age: 10
     spm_units:
       spm_unit:
-        members: [parent1, parent2, child]
+        members: [person1, person2, person3]
+        is_tanf_enrolled: true
     households:
       household:
-        members: [parent1, parent2, child]
+        members: [person1, person2, person3]
         state_code: IN
   output:
     in_tanf_countable_earned_income_for_eligibility: [187.6, 187.6, 187.6]
-    # 1 earner: $400 - $90 = $310
-    # Unit total: $310
+    # $400 - $90 = $310
     # $310 - $30 = $280
     # $280 * 0.67 = $187.60
 
-- name: Family of 3 with 2 earners - each gets $90 (total $180 disregard)
+- name: Case 2, enrolled family of 3 with 2 earners.
   period: 2024-01
+  absolute_error_margin: 0.1
   input:
     people:
-      parent1:
+      person1:
         tanf_gross_earned_income: 200
-      parent2:
+      person2:
         tanf_gross_earned_income: 200
-      child:
+      person3:
         age: 10
     spm_units:
       spm_unit:
-        members: [parent1, parent2, child]
+        members: [person1, person2, person3]
+        is_tanf_enrolled: true
     households:
       household:
-        members: [parent1, parent2, child]
+        members: [person1, person2, person3]
         state_code: IN
   output:
-    in_tanf_countable_earned_income_for_eligibility: [127.3, 127.3, 127.3]
-    # Parent1: $200 - $90 = $110
-    # Parent2: $200 - $90 = $110
-    # Unit total: $220 (vs $310 if only 1 earner had $400)
-    # $220 - $30 = $190
-    # $190 * 0.67 = $127.30
-    # Key: 2 earners = $180 disregard, 1 earner = $90 disregard
+    in_tanf_countable_earned_income_for_eligibility: [107.2, 107.2, 107.2]
+    # Per earner: ($200-$90-$30)*0.67 = $80*0.67 = $53.60
+    # Unit total: $53.60 + $53.60 = $107.20
 
-- name: Single earner with low income
+- name: Case 3, enrolled single earner with low income.
   period: 2024-01
+  absolute_error_margin: 0.1
   input:
     people:
       person1:
@@ -62,6 +66,7 @@
     spm_units:
       spm_unit:
         members: [person1, person2]
+        is_tanf_enrolled: true
     households:
       household:
         members: [person1, person2]
@@ -72,8 +77,9 @@
     # $210 - $30 = $180
     # $180 * 0.67 = $120.60
 
-- name: Earner below work expense disregard
+- name: Case 4, enrolled earner below work expense disregard.
   period: 2024-01
+  absolute_error_margin: 0.1
   input:
     people:
       person1:
@@ -83,6 +89,7 @@
     spm_units:
       spm_unit:
         members: [person1, person2]
+        is_tanf_enrolled: true
     households:
       household:
         members: [person1, person2]
@@ -90,11 +97,10 @@
   output:
     in_tanf_countable_earned_income_for_eligibility: [0, 0]
     # $50 - $90 = max(0, -40) = $0
-    # $0 - $30 = max(0, -30) = $0
-    # $0 * 0.67 = $0
 
-- name: Zero income
+- name: Case 5, enrolled with zero income.
   period: 2024-01
+  absolute_error_margin: 0.1
   input:
     people:
       person1:
@@ -104,9 +110,153 @@
     spm_units:
       spm_unit:
         members: [person1, person2]
+        is_tanf_enrolled: true
+    households:
+      household:
+        members: [person1, person2]
+        state_code: IN
+  output:
+    in_tanf_countable_earned_income_for_eligibility: [0, 0]
+
+# --- Per-earner deductions (all three disregards apply per individual) ---
+
+- name: Case 5b, enrolled 2 earners vs 1 earner with same total.
+  period: 2024-01
+  absolute_error_margin: 0.1
+  input:
+    people:
+      person1:
+        tanf_gross_earned_income: 200
+      person2:
+        tanf_gross_earned_income: 200
+      person3:
+        age: 10
+    spm_units:
+      spm_unit:
+        members: [person1, person2, person3]
+        is_tanf_enrolled: true
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: IN
+  output:
+    in_tanf_countable_earned_income_for_eligibility: [107.2, 107.2, 107.2]
+    # Per earner: ($200-$90-$30)*0.67 = $80*0.67 = $53.60
+    # Unit total: $53.60 + $53.60 = $107.20
+    # Compare Case 1 (1 earner at $400): ($400-$90-$30)*0.67 = $187.60
+    # 2 earners get more deductions ($90+$30 each = $240 total vs $120 for 1 earner)
+
+# --- Applicants (not enrolled, $90 work expense only) ---
+
+- name: Case 6, applicant with 1 earner.
+  period: 2024-01
+  absolute_error_margin: 0.1
+  input:
+    people:
+      person1:
+        tanf_gross_earned_income: 400
+      person2:
+        age: 10
+    spm_units:
+      spm_unit:
+        members: [person1, person2]
+        is_tanf_enrolled: false
+    households:
+      household:
+        members: [person1, person2]
+        state_code: IN
+  output:
+    in_tanf_countable_earned_income_for_eligibility: [310, 310]
+    # $400 - $90 = $310 (no $30 or 1/3 for applicants)
+
+- name: Case 7, applicant with low income.
+  period: 2024-01
+  absolute_error_margin: 0.1
+  input:
+    people:
+      person1:
+        tanf_gross_earned_income: 300
+      person2:
+        age: 10
+    spm_units:
+      spm_unit:
+        members: [person1, person2]
+        is_tanf_enrolled: false
+    households:
+      household:
+        members: [person1, person2]
+        state_code: IN
+  output:
+    in_tanf_countable_earned_income_for_eligibility: [210, 210]
+    # $300 - $90 = $210
+
+- name: Case 8, applicant below work expense.
+  period: 2024-01
+  absolute_error_margin: 0.1
+  input:
+    people:
+      person1:
+        tanf_gross_earned_income: 50
+      person2:
+        age: 10
+    spm_units:
+      spm_unit:
+        members: [person1, person2]
+        is_tanf_enrolled: false
     households:
       household:
         members: [person1, person2]
         state_code: IN
   output:
     in_tanf_countable_earned_income_for_eligibility: [0, 0]
+    # $50 - $90 = max(0, -40) = $0
+
+# --- YEAR period (exercises both calendar month paths) ---
+
+- name: Case 9, enrolled over full year.
+  period: 2024
+  absolute_error_margin: 0.1
+  input:
+    people:
+      person1:
+        tanf_gross_earned_income: 4_800
+      person2:
+        age: 10
+    spm_units:
+      spm_unit:
+        members: [person1, person2]
+        is_tanf_enrolled: true
+    households:
+      household:
+        members: [person1, person2]
+        state_code: IN
+  output:
+    in_tanf_countable_earned_income_for_eligibility: [2_990.4, 2_990.4]
+    # Monthly gross: $4,800 / 12 = $400
+    # $400 - $90 = $310, then $310 - $30 = $280
+    # Months 1-4 (phase 1): $280 * 0.67 = $187.60 x 4 = $750.40
+    # Months 5-12 (phase 2): $280 x 8 = $2,240.00
+    # Annual total: $750.40 + $2,240.00 = $2,990.40
+
+- name: Case 10, applicant over full year.
+  period: 2024
+  absolute_error_margin: 0.1
+  input:
+    people:
+      person1:
+        tanf_gross_earned_income: 4_800
+      person2:
+        age: 10
+    spm_units:
+      spm_unit:
+        members: [person1, person2]
+        is_tanf_enrolled: false
+    households:
+      household:
+        members: [person1, person2]
+        state_code: IN
+  output:
+    in_tanf_countable_earned_income_for_eligibility: [3_720, 3_720]
+    # Monthly gross: $4,800 / 12 = $400
+    # All 12 months: $400 - $90 = $310
+    # Annual total: $310 x 12 = $3,720
diff --git a/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/integration.yaml b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/integration.yaml
index fa34c564035..d10029f4651 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/integration.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/integration.yaml
@@ -49,6 +49,7 @@
     spm_units:
       spm_unit:
         members: [person1, person2]
+        is_tanf_enrolled: true
         spm_unit_cash_assets: 800
     households:
       household:
@@ -63,7 +64,7 @@
     # $200 × 0.25 (75% disregard) = $50
     in_tanf_countable_income_for_payment: [50, 50]
     in_tanf_countable_income_eligible: [true, true]
-    # Countable for elig ($53.60) < standard of need ($255) → eligible
+    # Enrolled: countable for elig ($53.60) < 100% FPL for 2 → eligible
     in_tanf_payment_eligible: [true, true]
     # Countable for benefit ($50) < standard of need ($255) → eligible
     in_tanf_payment_standard: [255, 255]
@@ -85,6 +86,7 @@
     spm_units:
       spm_unit:
         members: [person1, person2]
+        is_tanf_enrolled: true
         spm_unit_cash_assets: 700
     households:
       household:
@@ -101,7 +103,7 @@
     in_tanf_countable_income_for_payment: [175, 175]
     # $75 (earned) + $100 (unearned) = $175
     in_tanf_countable_income_eligible: [true, true]
-    # Countable for elig ($220.60) < standard of need ($255) → eligible
+    # Enrolled: countable for elig ($220.60) < 100% FPL for 2 → eligible
     in_tanf_payment_eligible: [true, true]
     # Countable for benefit ($175) < standard of need ($255) → eligible
     in_tanf_payment_standard: [255, 255]
@@ -109,7 +111,7 @@
     in_tanf: [80, 80]
     # Max benefit ($255) - countable income ($175) = $80
 
-- name: Case 4 - High earner exceeds eligibility threshold
+- name: Case 4 - Applicant high earner exceeds eligibility threshold
   period: 2024-01
   input:
     people:
@@ -123,6 +125,7 @@
     spm_units:
       spm_unit:
         members: [person1, person2, person3]
+        is_tanf_enrolled: false
         spm_unit_cash_assets: 900
     households:
       household:
@@ -130,14 +133,14 @@
         state_code: IN
   output:
     spm_unit_size: [3, 3, 3]
-    in_tanf_countable_earned_income_for_eligibility: [321.6, 321.6, 321.6]
-    # $600 - $90 = $510 → $510 - $30 = $480 → $480 * 0.67 = $321.60
-    in_tanf_countable_income_for_eligibility: [321.6, 321.6, 321.6]
+    in_tanf_countable_earned_income_for_eligibility: [510, 510, 510]
+    # Applicant: $600 - $90 = $510 ($90 work expense only)
+    in_tanf_countable_income_for_eligibility: [510, 510, 510]
     in_tanf_countable_earned_income: [150, 150, 150]
     # $600 × 0.25 = $150
     in_tanf_countable_income_for_payment: [150, 150, 150]
     in_tanf_countable_income_eligible: [false, false, false]
-    # Countable for elig ($321.60) >= standard of need ($320) → NOT eligible
+    # Applicant threshold = standard of need ($320); $510 >= $320 → NOT eligible
     in_tanf_payment_eligible: [true, true, true]
     # Countable for benefit ($150) < standard of need ($320) → eligible
     in_tanf_payment_standard: [320, 320, 320]
@@ -161,6 +164,7 @@
     spm_units:
       spm_unit:
         members: [person1, person2, person3, person4]
+        is_tanf_enrolled: true
         spm_unit_cash_assets: 1_500
     households:
       household:
@@ -175,7 +179,7 @@
     # $300 × 0.25 = $75
     in_tanf_countable_income_for_payment: [75, 75, 75, 75]
     in_tanf_countable_income_eligible: [true, true, true, true]
-    # Countable for elig ($120.60) < standard of need ($385) → eligible
+    # Enrolled: countable for elig ($120.60) < 100% FPL for 4 → eligible
     in_tanf_payment_eligible: [true, true, true, true]
     # Countable for benefit ($75) < standard of need ($385) → eligible
     in_tanf_payment_standard: [385, 385, 385, 385]
@@ -199,6 +203,7 @@
     spm_units:
       spm_unit:
         members: [person1, person2, person3]
+        is_tanf_enrolled: true
         spm_unit_cash_assets: 500
     households:
       household:
@@ -206,16 +211,15 @@
         state_code: IN
   output:
     spm_unit_size: [3, 3, 3]
-    in_tanf_countable_earned_income_for_eligibility: [127.3, 127.3, 127.3]
-    # Person1: $200 - $90 = $110
-    # Person2: $200 - $90 = $110
-    # Unit total: $220 - $30 = $190 → $190 * 0.67 = $127.30
-    in_tanf_countable_income_for_eligibility: [127.3, 127.3, 127.3]
+    in_tanf_countable_earned_income_for_eligibility: [107.2, 107.2, 107.2]
+    # Per earner: ($200-$90-$30)*0.67 = $80*0.67 = $53.60
+    # Unit total: $53.60 + $53.60 = $107.20
+    in_tanf_countable_income_for_eligibility: [107.2, 107.2, 107.2]
     in_tanf_countable_earned_income: [100, 100, 100]
     # ($200 + $200) × 0.25 = $100
     in_tanf_countable_income_for_payment: [100, 100, 100]
     in_tanf_countable_income_eligible: [true, true, true]
-    # Countable for elig ($127.30) < standard of need ($320) → eligible
+    # Countable for elig ($107.20) < FPG for 3 → eligible
     in_tanf_payment_eligible: [true, true, true]
     # Countable for benefit ($100) < standard of need ($320) → eligible
     in_tanf_payment_standard: [320, 320, 320]
@@ -247,3 +251,114 @@
     in_tanf_eligible: false
     # Single adult with no children → not demographically eligible
     in_tanf: 0
+
+- name: Case 8, enrolled family with 2018 historical parameters.
+  period: 2018
+  absolute_error_margin: 0.1
+  input:
+    people:
+      person1:
+        age: 30
+        tanf_gross_earned_income: 3_600
+      person2:
+        age: 10
+      person3:
+        age: 8
+    spm_units:
+      spm_unit:
+        members: [person1, person2, person3]
+        is_tanf_enrolled: true
+        spm_unit_cash_assets: 500
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: IN
+  output:
+    in_tanf_countable_earned_income_for_eligibility: [1_922.4, 1_922.4, 1_922.4]
+    # Monthly gross: $3,600 / 12 = $300
+    # Months 1-4 (phase 1): ($300-$90-$30)*0.67 = $120.60 x 4 = $482.40
+    # Months 5-12 (phase 2): $300-$90-$30 = $180 x 8 = $1,440
+    # Annual: $482.40 + $1,440 = $1,922.40
+    in_tanf_countable_income_for_eligibility: [1_922.4, 1_922.4, 1_922.4]
+    in_tanf_countable_earned_income: [900, 900, 900]
+    # $300 x 0.25 = $75/month x 12 = $900
+    in_tanf_countable_income_for_payment: [900, 900, 900]
+    in_tanf_payment_standard: [3_456, 3_456, 3_456]
+    # Family of 3, 2018 (pre-2023): $288/month x 12 = $3,456
+    in_tanf: [2_556, 2_556, 2_556]
+    # ($288 - $75) x 12 = $213 x 12 = $2,556
+
+- name: Case 9, applicant with earned income.
+  period: 2024-01
+  absolute_error_margin: 0.1
+  input:
+    people:
+      person1:
+        age: 28
+        tanf_gross_earned_income: 200
+      person2:
+        age: 5
+    spm_units:
+      spm_unit:
+        members: [person1, person2]
+        is_tanf_enrolled: false
+        spm_unit_cash_assets: 800
+    households:
+      household:
+        members: [person1, person2]
+        state_code: IN
+  output:
+    spm_unit_size: [2, 2]
+    in_tanf_countable_earned_income_for_eligibility: [110, 110]
+    # Applicant: $200 - $90 = $110 ($90 work expense only)
+    in_tanf_countable_income_for_eligibility: [110, 110]
+    in_tanf_countable_earned_income: [50, 50]
+    # $200 x 0.25 = $50
+    in_tanf_countable_income_for_payment: [50, 50]
+    in_tanf_countable_income_eligible: [true, true]
+    # Applicant threshold = standard of need ($255); $110 < $255 → eligible
+    in_tanf_payment_eligible: [true, true]
+    in_tanf_payment_standard: [255, 255]
+    in_tanf_eligible: [true, true]
+    in_tanf: [205, 205]
+    # $255 - $50 = $205
+
+- name: Case 10, applicant with mixed income near threshold.
+  period: 2024-01
+  absolute_error_margin: 0.1
+  input:
+    people:
+      person1:
+        age: 35
+        tanf_gross_earned_income: 300
+      person2:
+        age: 12
+        tanf_gross_unearned_income: 100
+      person3:
+        age: 8
+    spm_units:
+      spm_unit:
+        members: [person1, person2, person3]
+        is_tanf_enrolled: false
+        spm_unit_cash_assets: 500
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: IN
+  output:
+    spm_unit_size: [3, 3, 3]
+    in_tanf_countable_earned_income_for_eligibility: [210, 210, 210]
+    # Applicant: $300 - $90 = $210 ($90 work expense only)
+    in_tanf_countable_income_for_eligibility: [310, 310, 310]
+    # $210 (earned) + $100 (unearned) = $310
+    in_tanf_countable_earned_income: [75, 75, 75]
+    # $300 x 0.25 = $75
+    in_tanf_countable_income_for_payment: [175, 175, 175]
+    # $75 + $100 = $175
+    in_tanf_countable_income_eligible: [true, true, true]
+    # Applicant threshold = standard of need ($320); $310 < $320 → eligible
+    in_tanf_payment_eligible: [true, true, true]
+    in_tanf_payment_standard: [320, 320, 320]
+    in_tanf_eligible: [true, true, true]
+    in_tanf: [145, 145, 145]
+    # $320 - $175 = $145
diff --git a/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/integration_historical.yaml b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/integration_historical.yaml
new file mode 100644
index 00000000000..e25d5ec2b0c
--- /dev/null
+++ b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/integration_historical.yaml
@@ -0,0 +1,108 @@
+# Historical integration tests (pre-SEA 265 era)
+# Tests the full benefit calculation pipeline with 1997-2023 parameter values
+
+- name: Pre-reform family of 3 with no income receives $288
+  period: 2020-01
+  input:
+    people:
+      person1:
+        age: 30
+        tanf_gross_earned_income: 0
+        tanf_gross_unearned_income: 0
+      person2:
+        age: 10
+      person3:
+        age: 8
+    spm_units:
+      spm_unit:
+        members: [person1, person2, person3]
+        spm_unit_cash_assets: 500
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: IN
+  output:
+    in_tanf_payment_standard: [288, 288, 288]
+    in_tanf_countable_income_for_payment: [0, 0, 0]
+    in_tanf_countable_income_eligible: [true, true, true]
+    in_tanf_payment_eligible: [true, true, true]
+    in_tanf: [288, 288, 288]
+
+- name: Pre-reform family of 3 with earned income
+  period: 2020-01
+  input:
+    people:
+      person1:
+        age: 28
+        tanf_gross_earned_income: 200
+      person2:
+        age: 5
+      person3:
+        age: 3
+    spm_units:
+      spm_unit:
+        members: [person1, person2, person3]
+        is_tanf_enrolled: true
+        spm_unit_cash_assets: 800
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: IN
+  output:
+    in_tanf_payment_standard: [288, 288, 288]
+    in_tanf_countable_earned_income: [50, 50, 50]
+    # $200 * 0.25 = $50
+    in_tanf_countable_income_for_payment: [50, 50, 50]
+    in_tanf_countable_earned_income_for_eligibility: [53.6, 53.6, 53.6]
+    # $200 - $90 = $110 -> $110 - $30 = $80 -> $80 * 0.67 = $53.60
+    in_tanf_countable_income_for_eligibility: [53.6, 53.6, 53.6]
+    in_tanf_countable_income_eligible: [true, true, true]
+    in_tanf_payment_eligible: [true, true, true]
+    in_tanf: [238, 238, 238]
+    # $288 - $50 = $238
+
+- name: Pre-reform January 2023 family of 3 gets old benefit
+  period: 2023-01
+  input:
+    people:
+      person1:
+        age: 30
+        tanf_gross_earned_income: 0
+      person2:
+        age: 10
+      person3:
+        age: 8
+    spm_units:
+      spm_unit:
+        members: [person1, person2, person3]
+        spm_unit_cash_assets: 500
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: IN
+  output:
+    in_tanf_payment_standard: [288, 288, 288]
+    in_tanf: [288, 288, 288]
+
+- name: Post-reform January 2024 family of 3 gets new benefit
+  period: 2024-01
+  input:
+    people:
+      person1:
+        age: 30
+        tanf_gross_earned_income: 0
+      person2:
+        age: 10
+      person3:
+        age: 8
+    spm_units:
+      spm_unit:
+        members: [person1, person2, person3]
+        spm_unit_cash_assets: 500
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: IN
+  output:
+    in_tanf_payment_standard: [320, 320, 320]
+    in_tanf: [320, 320, 320]
diff --git a/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/resources/in_tanf_resources_eligible_historical.yaml b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/resources/in_tanf_resources_eligible_historical.yaml
new file mode 100644
index 00000000000..48605cc4970
--- /dev/null
+++ b/policyengine_us/tests/policy/baseline/gov/states/in/fssa/tanf/resources/in_tanf_resources_eligible_historical.yaml
@@ -0,0 +1,58 @@
+# Historical resource eligibility tests (pre-SEA 265)
+# While-receiving limit was $1,500 before July 2023, changed to $10,000
+
+- name: Pre-reform enrolled family at $1,400 passes (under $1,500 limit)
+  period: 2020-01
+  input:
+    state_code: IN
+    in_tanf_countable_resources: 1_400
+    is_tanf_enrolled: true
+  output:
+    in_tanf_resources_eligible: true
+
+- name: Pre-reform enrolled family at $1,500 passes (at $1,500 limit)
+  period: 2020-01
+  input:
+    state_code: IN
+    in_tanf_countable_resources: 1_500
+    is_tanf_enrolled: true
+  output:
+    in_tanf_resources_eligible: true
+
+- name: Pre-reform enrolled family at $1,501 fails (over $1,500 limit)
+  period: 2020-01
+  input:
+    state_code: IN
+    in_tanf_countable_resources: 1_501
+    is_tanf_enrolled: true
+  output:
+    in_tanf_resources_eligible: false
+
+- name: Pre-reform applicant at $999 passes (under $1,000 limit)
+  period: 2020-01
+  input:
+    state_code: IN
+    in_tanf_countable_resources: 999
+    is_tanf_enrolled: false
+  output:
+    in_tanf_resources_eligible: true
+
+# Transition boundary tests
+
+- name: Pre-reform 2021 enrolled at $5,000 fails (old $1,500 limit)
+  period: 2021-01
+  input:
+    state_code: IN
+    in_tanf_countable_resources: 5_000
+    is_tanf_enrolled: true
+  output:
+    in_tanf_resources_eligible: false
+
+- name: Post-reform 2024 enrolled at $5,000 passes (new $10,000 limit)
+  period: 2024-01
+  input:
+    state_code: IN
+    in_tanf_countable_resources: 5_000
+    is_tanf_enrolled: true
+  output:
+    in_tanf_resources_eligible: true
diff --git a/policyengine_us/variables/gov/states/in/fssa/tanf/income/in_tanf_countable_earned_income_for_eligibility.py b/policyengine_us/variables/gov/states/in/fssa/tanf/income/in_tanf_countable_earned_income_for_eligibility.py
index f6a7d0beac4..95304a7552f 100644
--- a/policyengine_us/variables/gov/states/in/fssa/tanf/income/in_tanf_countable_earned_income_for_eligibility.py
+++ b/policyengine_us/variables/gov/states/in/fssa/tanf/income/in_tanf_countable_earned_income_for_eligibility.py
@@ -16,18 +16,37 @@ class in_tanf_countable_earned_income_for_eligibility(Variable):
     defined_for = StateCode.IN
 
     def formula(spm_unit, period, parameters):
-        # NOTE: The $30 and 1/3 disregard only applies for the first 4 months
-        # of continuing eligibility. This simplified implementation always
-        # applies the $30 and 1/3 disregard.
+        # NOTE: Uses calendar month as proxy for benefit duration.
+        # Actual policy tracks cumulative months since enrollment.
+        # All deductions ($90 work expense, $30 flat, 1/3 disregard)
+        # are applied per earner per 470 IAC 10.3-4-4(c).
         p = parameters(period).gov.states["in"].fssa.tanf.income.deductions
         person = spm_unit.members
         gross_earned = person("tanf_gross_earned_income", period)
 
-        # $90 per earner, then $30 + 1/3 per unit (470 IAC 10.3-4-4(c))
-        after_work_expense = spm_unit.sum(
-            max_(gross_earned - p.work_expense.amount, 0)
-        )
+        # (c)(1): $90 per earner
+        after_work_expense = max_(gross_earned - p.work_expense.amount, 0)
+
+        is_enrolled = person.spm_unit("is_tanf_enrolled", period)
+        month = period.start.month
+
+        # (c)(2): $30 per earner (enrolled, months 1-12)
         after_flat = max_(
             after_work_expense - p.eligibility.flat_disregard.amount, 0
         )
-        return after_flat * (1 - p.eligibility.earned_income_disregard.rate)
+
+        # (c)(3): 1/3 per earner (enrolled, months 1-4 only)
+        in_one_third_phase = (
+            month <= p.eligibility.earned_income_disregard.months
+        )
+        with_one_third = after_flat * (
+            1 - p.eligibility.earned_income_disregard.rate
+        )
+        enrolled_countable = where(
+            in_one_third_phase, with_one_third, after_flat
+        )
+
+        # Sum per-earner results to unit level
+        return spm_unit.sum(
+            where(is_enrolled, enrolled_countable, after_work_expense)
+        )