From fb7827983a4a0e81c78f95792011ccc9ac8feb19 Mon Sep 17 00:00:00 2001
From: PavelMakarchuk <pavel.ma99@gmail.com>
Date: Thu, 9 Apr 2026 11:17:00 -0400
Subject: [PATCH 1/7] Add Idaho senior deduction conformity

---
 .../id-hb559-senior-deduction.fixed.md        |  1 +
 .../tax/income/subtractions/subtractions.yaml |  3 ++
 .../gov/states/id/tax/income/integration.yaml | 37 +++++++++++++++++++
 .../id_additional_senior_deduction.yaml       | 28 ++++++++++++++
 .../id_additional_senior_deduction.py         | 17 +++++++++
 5 files changed, 86 insertions(+)
 create mode 100644 changelog.d/id-hb559-senior-deduction.fixed.md
 create mode 100644 policyengine_us/tests/policy/baseline/gov/states/id/tax/income/subtractions/id_additional_senior_deduction.yaml
 create mode 100644 policyengine_us/variables/gov/states/id/tax/income/subtractions/id_additional_senior_deduction.py

diff --git a/changelog.d/id-hb559-senior-deduction.fixed.md b/changelog.d/id-hb559-senior-deduction.fixed.md
new file mode 100644
index 00000000000..163623703e3
--- /dev/null
+++ b/changelog.d/id-hb559-senior-deduction.fixed.md
@@ -0,0 +1 @@
+Added Idaho conformity to the federal enhanced senior deduction by subtracting the federal additional senior deduction from Idaho income starting in 2025.
diff --git a/policyengine_us/parameters/gov/states/id/tax/income/subtractions/subtractions.yaml b/policyengine_us/parameters/gov/states/id/tax/income/subtractions/subtractions.yaml
index b10946218af..9dda4918ef0 100644
--- a/policyengine_us/parameters/gov/states/id/tax/income/subtractions/subtractions.yaml
+++ b/policyengine_us/parameters/gov/states/id/tax/income/subtractions/subtractions.yaml
@@ -15,6 +15,7 @@ values:
     - us_govt_interest # (3)(a)
     - military_service_income # (4)
     - taxable_social_security # (5)
+    - id_additional_senior_deduction # per HB 559 / OBBBA conformity
     - id_household_and_dependent_care_expense_deduction # (6)
     - id_aged_or_disabled_deduction # (8)
     - id_capital_gains_deduction # (10)
@@ -34,5 +35,7 @@ metadata:
     href: https://tax.idaho.gov/wp-content/uploads/forms/EIN00046/EIN00046_11-15-2021.pdf#page=30
   - title: Idaho Individual Income Tax Instructions Packet 2025
     href: https://tax.idaho.gov/wp-content/uploads/forms/EIN00046/EIN00046_09-29-2025.pdf#page=32
+  - title: Idaho taxpayers can now file 2025 returns to claim new conformity deductions
+    href: https://tax.idaho.gov/pressrelease/update-on-filing-2025-idaho-income-taxes-now-that-conformity-is-law/
   - title: Section 35.01.01.254 - (5) / (3) (a)
     href: https://regulations.justia.com/states/idaho/35/35-01-01/section-35-01-01-254/
diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml
index 775a31e31f8..5dc7fe92a8f 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml
@@ -228,3 +228,40 @@
   output:
     # Grocery credit: 2 people * $155 = $310 (aged credit not in effect for 2025)
     id_grocery_credit: 310
+
+- name: Idaho joint senior filers receive the OBBBA enhanced senior deduction in 2025
+  absolute_error_margin: 0.01
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 70
+        taxable_interest_income: 100_000
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+      person2:
+        age: 70
+        taxable_interest_income: 100_000
+        is_tax_unit_spouse: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+        itemized_taxable_income_deductions: 60_000
+        id_salt_deduction: 0
+    spm_units:
+      spm_unit:
+        members: [person1, person2]
+        snap: 0
+        tanf: 0
+    households:
+      household:
+        members: [person1, person2]
+        state_fips: 16
+  output:
+    additional_senior_deduction: 9_000
+    id_additional_senior_deduction: 9_000
+    id_taxable_income: 131_000
diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/subtractions/id_additional_senior_deduction.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/subtractions/id_additional_senior_deduction.yaml
new file mode 100644
index 00000000000..aaea6384373
--- /dev/null
+++ b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/subtractions/id_additional_senior_deduction.yaml
@@ -0,0 +1,28 @@
+- name: Idaho conforms to the federal additional senior deduction in 2025.
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 70
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+      person2:
+        age: 70
+        is_tax_unit_spouse: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+        adjusted_gross_income: 200_000
+        salt_deduction: 0
+        standard_deduction: 0
+    households:
+      household:
+        members: [person1, person2]
+        state_code: ID
+  output:
+    additional_senior_deduction: 9_000
+    id_additional_senior_deduction: 9_000
diff --git a/policyengine_us/variables/gov/states/id/tax/income/subtractions/id_additional_senior_deduction.py b/policyengine_us/variables/gov/states/id/tax/income/subtractions/id_additional_senior_deduction.py
new file mode 100644
index 00000000000..bbbfb2a5572
--- /dev/null
+++ b/policyengine_us/variables/gov/states/id/tax/income/subtractions/id_additional_senior_deduction.py
@@ -0,0 +1,17 @@
+from policyengine_us.model_api import *
+
+
+class id_additional_senior_deduction(Variable):
+    value_type = float
+    entity = TaxUnit
+    label = "Idaho additional senior deduction"
+    unit = USD
+    definition_period = YEAR
+    defined_for = StateCode.ID
+    reference = (
+        "https://legislature.idaho.gov/sessioninfo/2026/legislation/H0559/",
+        "https://tax.idaho.gov/pressrelease/update-on-filing-2025-idaho-income-taxes-now-that-conformity-is-law/",
+    )
+
+    def formula(tax_unit, period, parameters):
+        return tax_unit("additional_senior_deduction", period)

From 56857be458ff64d7d49fbf759b2775baf0cb7e99 Mon Sep 17 00:00:00 2001
From: PavelMakarchuk <pavel.ma99@gmail.com>
Date: Fri, 10 Apr 2026 10:07:47 -0400
Subject: [PATCH 2/7] Move Idaho senior deduction to line 18 path

---
 .../id-hb559-senior-deduction.fixed.md        |  2 +-
 .../tax/income/subtractions/subtractions.yaml |  3 ---
 .../id_additional_senior_deduction.yaml       |  0
 .../deductions/id_line_18_deductions.yaml     |  8 ++++++++
 .../id/tax/income/id_taxable_income.yaml      | 16 +++++++++++++---
 .../gov/states/id/tax/income/integration.yaml |  1 +
 .../id_additional_senior_deduction.py         |  0
 .../id/tax/income/deductions/id_deductions.py |  2 +-
 .../deductions/id_line_18_deductions.py       | 19 +++++++++++++++++++
 .../states/id/tax/income/id_taxable_income.py |  6 +++---
 10 files changed, 46 insertions(+), 11 deletions(-)
 rename policyengine_us/tests/policy/baseline/gov/states/id/tax/income/{subtractions => deductions}/id_additional_senior_deduction.yaml (100%)
 create mode 100644 policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_line_18_deductions.yaml
 rename policyengine_us/variables/gov/states/id/tax/income/{subtractions => deductions}/id_additional_senior_deduction.py (100%)
 create mode 100644 policyengine_us/variables/gov/states/id/tax/income/deductions/id_line_18_deductions.py

diff --git a/changelog.d/id-hb559-senior-deduction.fixed.md b/changelog.d/id-hb559-senior-deduction.fixed.md
index 163623703e3..d6dcacb37f8 100644
--- a/changelog.d/id-hb559-senior-deduction.fixed.md
+++ b/changelog.d/id-hb559-senior-deduction.fixed.md
@@ -1 +1 @@
-Added Idaho conformity to the federal enhanced senior deduction by subtracting the federal additional senior deduction from Idaho income starting in 2025.
+Added Idaho conformity to the federal enhanced senior deduction on the Idaho Form 40 line 18 deduction path starting in 2025.
diff --git a/policyengine_us/parameters/gov/states/id/tax/income/subtractions/subtractions.yaml b/policyengine_us/parameters/gov/states/id/tax/income/subtractions/subtractions.yaml
index 9dda4918ef0..b10946218af 100644
--- a/policyengine_us/parameters/gov/states/id/tax/income/subtractions/subtractions.yaml
+++ b/policyengine_us/parameters/gov/states/id/tax/income/subtractions/subtractions.yaml
@@ -15,7 +15,6 @@ values:
     - us_govt_interest # (3)(a)
     - military_service_income # (4)
     - taxable_social_security # (5)
-    - id_additional_senior_deduction # per HB 559 / OBBBA conformity
     - id_household_and_dependent_care_expense_deduction # (6)
     - id_aged_or_disabled_deduction # (8)
     - id_capital_gains_deduction # (10)
@@ -35,7 +34,5 @@ metadata:
     href: https://tax.idaho.gov/wp-content/uploads/forms/EIN00046/EIN00046_11-15-2021.pdf#page=30
   - title: Idaho Individual Income Tax Instructions Packet 2025
     href: https://tax.idaho.gov/wp-content/uploads/forms/EIN00046/EIN00046_09-29-2025.pdf#page=32
-  - title: Idaho taxpayers can now file 2025 returns to claim new conformity deductions
-    href: https://tax.idaho.gov/pressrelease/update-on-filing-2025-idaho-income-taxes-now-that-conformity-is-law/
   - title: Section 35.01.01.254 - (5) / (3) (a)
     href: https://regulations.justia.com/states/idaho/35/35-01-01/section-35-01-01-254/
diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/subtractions/id_additional_senior_deduction.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml
similarity index 100%
rename from policyengine_us/tests/policy/baseline/gov/states/id/tax/income/subtractions/id_additional_senior_deduction.yaml
rename to policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml
diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_line_18_deductions.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_line_18_deductions.yaml
new file mode 100644
index 00000000000..d0c3558ab88
--- /dev/null
+++ b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_line_18_deductions.yaml
@@ -0,0 +1,8 @@
+- name: Idaho line 18 includes QBID and federal Schedule 1-A deductions
+  period: 2025
+  input:
+    qualified_business_income_deduction: 2_000
+    id_additional_senior_deduction: 9_000
+    state_code: ID
+  output:
+    id_line_18_deductions: 11_000
diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/id_taxable_income.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/id_taxable_income.yaml
index 80309f2e9dd..c11bc036cd7 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/id_taxable_income.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/id_taxable_income.yaml
@@ -12,17 +12,27 @@
   input:
     id_agi: 500
     id_deductions: 1_000
-    qualified_business_income_deduction: 200
+    id_line_18_deductions: 200
     state_code: ID
   output:
     id_taxable_income: 0
 
-- name: AGI after deductions is reduced by QBID
+- name: AGI after deductions is reduced by Idaho line 18 deductions
   period: 2021
   input:
     id_agi: 1_000
     id_deductions: 500
-    qualified_business_income_deduction: 300
+    id_line_18_deductions: 300
     state_code: ID
   output:
     id_taxable_income: 200
+
+- name: Idaho line 18 deductions include the federal senior deduction in 2025
+  period: 2025
+  input:
+    id_agi: 200_000
+    id_deductions: 60_000
+    id_line_18_deductions: 9_000
+    state_code: ID
+  output:
+    id_taxable_income: 131_000
diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml
index 5dc7fe92a8f..6a92a4af795 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml
@@ -264,4 +264,5 @@
   output:
     additional_senior_deduction: 9_000
     id_additional_senior_deduction: 9_000
+    id_line_18_deductions: 9_000
     id_taxable_income: 131_000
diff --git a/policyengine_us/variables/gov/states/id/tax/income/subtractions/id_additional_senior_deduction.py b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_additional_senior_deduction.py
similarity index 100%
rename from policyengine_us/variables/gov/states/id/tax/income/subtractions/id_additional_senior_deduction.py
rename to policyengine_us/variables/gov/states/id/tax/income/deductions/id_additional_senior_deduction.py
diff --git a/policyengine_us/variables/gov/states/id/tax/income/deductions/id_deductions.py b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_deductions.py
index 4d1b6f308c3..460511569ae 100644
--- a/policyengine_us/variables/gov/states/id/tax/income/deductions/id_deductions.py
+++ b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_deductions.py
@@ -16,5 +16,5 @@ class id_deductions(Variable):
     def formula(tax_unit, period, parameters):
         itm_ded = tax_unit("id_itemized_deductions", period)
         std_ded = tax_unit("standard_deduction", period)
-        # We do not model qualified business income deduction for Idaho
+        # Idaho Form 40 line 18 deductions are modeled separately.
         return max_(itm_ded, std_ded)
diff --git a/policyengine_us/variables/gov/states/id/tax/income/deductions/id_line_18_deductions.py b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_line_18_deductions.py
new file mode 100644
index 00000000000..1bec19e5e87
--- /dev/null
+++ b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_line_18_deductions.py
@@ -0,0 +1,19 @@
+from policyengine_us.model_api import *
+
+
+class id_line_18_deductions(Variable):
+    value_type = float
+    entity = TaxUnit
+    label = "Idaho Form 40 line 18 deductions"
+    unit = USD
+    definition_period = YEAR
+    defined_for = StateCode.ID
+    reference = (
+        "https://tax.idaho.gov/wp-content/uploads/forms/EIN00046/EIN00046_03-02-2026.pdf",
+        "https://tax.idaho.gov/pressrelease/update-on-filing-2025-idaho-income-taxes-now-that-conformity-is-law/",
+    )
+
+    adds = [
+        "qualified_business_income_deduction",
+        "id_additional_senior_deduction",
+    ]
diff --git a/policyengine_us/variables/gov/states/id/tax/income/id_taxable_income.py b/policyengine_us/variables/gov/states/id/tax/income/id_taxable_income.py
index fe4e3b7e173..b9a30edd777 100644
--- a/policyengine_us/variables/gov/states/id/tax/income/id_taxable_income.py
+++ b/policyengine_us/variables/gov/states/id/tax/income/id_taxable_income.py
@@ -8,11 +8,11 @@ class id_taxable_income(Variable):
     unit = USD
     documentation = "Idaho taxable income"
     definition_period = YEAR
-    reference = "https://tax.idaho.gov/wp-content/uploads/forms/EFO00089/EFO00089_12-30-2022.pdf#page=1"
+    reference = "https://tax.idaho.gov/wp-content/uploads/forms/EIN00046/EIN00046_03-02-2026.pdf"
     defined_for = StateCode.ID
 
     def formula(tax_unit, period, parameters):
         agi = tax_unit("id_agi", period)
         deductions = tax_unit("id_deductions", period)
-        qbid = tax_unit("qualified_business_income_deduction", period)
-        return max_(0, agi - deductions - qbid)
+        line_18_deductions = tax_unit("id_line_18_deductions", period)
+        return max_(0, agi - deductions - line_18_deductions)

From b2fae500a8835334dc0c11b00d6bfb13a4921602 Mon Sep 17 00:00:00 2001
From: PavelMakarchuk <pavel.ma99@gmail.com>
Date: Fri, 10 Apr 2026 10:28:30 -0400
Subject: [PATCH 3/7] Use official wording for Idaho conformity deduction

---
 changelog.d/id-hb559-senior-deduction.fixed.md         |  2 +-
 .../tax/income/deductions/id_line_18_deductions.yaml   |  8 --------
 ...ness_income_and_federal_schedule_1a_deductions.yaml |  8 ++++++++
 .../gov/states/id/tax/income/id_taxable_income.yaml    | 10 +++++-----
 .../baseline/gov/states/id/tax/income/integration.yaml |  2 +-
 .../states/id/tax/income/deductions/id_deductions.py   |  3 ++-
 ...iness_income_and_federal_schedule_1a_deductions.py} |  4 ++--
 .../gov/states/id/tax/income/id_taxable_income.py      |  7 +++++--
 8 files changed, 24 insertions(+), 20 deletions(-)
 delete mode 100644 policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_line_18_deductions.yaml
 create mode 100644 policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_qualified_business_income_and_federal_schedule_1a_deductions.yaml
 rename policyengine_us/variables/gov/states/id/tax/income/deductions/{id_line_18_deductions.py => id_qualified_business_income_and_federal_schedule_1a_deductions.py} (75%)

diff --git a/changelog.d/id-hb559-senior-deduction.fixed.md b/changelog.d/id-hb559-senior-deduction.fixed.md
index d6dcacb37f8..6a0fae51447 100644
--- a/changelog.d/id-hb559-senior-deduction.fixed.md
+++ b/changelog.d/id-hb559-senior-deduction.fixed.md
@@ -1 +1 @@
-Added Idaho conformity to the federal enhanced senior deduction on the Idaho Form 40 line 18 deduction path starting in 2025.
+Added Idaho conformity to the federal enhanced senior deduction through Idaho's qualified business income and federal Schedule 1-A deduction path starting in 2025.
diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_line_18_deductions.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_line_18_deductions.yaml
deleted file mode 100644
index d0c3558ab88..00000000000
--- a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_line_18_deductions.yaml
+++ /dev/null
@@ -1,8 +0,0 @@
-- name: Idaho line 18 includes QBID and federal Schedule 1-A deductions
-  period: 2025
-  input:
-    qualified_business_income_deduction: 2_000
-    id_additional_senior_deduction: 9_000
-    state_code: ID
-  output:
-    id_line_18_deductions: 11_000
diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_qualified_business_income_and_federal_schedule_1a_deductions.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_qualified_business_income_and_federal_schedule_1a_deductions.yaml
new file mode 100644
index 00000000000..e6f30277308
--- /dev/null
+++ b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_qualified_business_income_and_federal_schedule_1a_deductions.yaml
@@ -0,0 +1,8 @@
+- name: Idaho qualified business income and federal Schedule 1-A deductions include the senior deduction
+  period: 2025
+  input:
+    qualified_business_income_deduction: 2_000
+    id_additional_senior_deduction: 9_000
+    state_code: ID
+  output:
+    id_qualified_business_income_and_federal_schedule_1a_deductions: 11_000
diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/id_taxable_income.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/id_taxable_income.yaml
index c11bc036cd7..882cb6a78d3 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/id_taxable_income.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/id_taxable_income.yaml
@@ -12,27 +12,27 @@
   input:
     id_agi: 500
     id_deductions: 1_000
-    id_line_18_deductions: 200
+    id_qualified_business_income_and_federal_schedule_1a_deductions: 200
     state_code: ID
   output:
     id_taxable_income: 0
 
-- name: AGI after deductions is reduced by Idaho line 18 deductions
+- name: AGI after deductions is reduced by Idaho conformity deductions
   period: 2021
   input:
     id_agi: 1_000
     id_deductions: 500
-    id_line_18_deductions: 300
+    id_qualified_business_income_and_federal_schedule_1a_deductions: 300
     state_code: ID
   output:
     id_taxable_income: 200
 
-- name: Idaho line 18 deductions include the federal senior deduction in 2025
+- name: Idaho conformity deductions include the federal senior deduction in 2025
   period: 2025
   input:
     id_agi: 200_000
     id_deductions: 60_000
-    id_line_18_deductions: 9_000
+    id_qualified_business_income_and_federal_schedule_1a_deductions: 9_000
     state_code: ID
   output:
     id_taxable_income: 131_000
diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml
index 6a92a4af795..12b4399c2fd 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml
@@ -264,5 +264,5 @@
   output:
     additional_senior_deduction: 9_000
     id_additional_senior_deduction: 9_000
-    id_line_18_deductions: 9_000
+    id_qualified_business_income_and_federal_schedule_1a_deductions: 9_000
     id_taxable_income: 131_000
diff --git a/policyengine_us/variables/gov/states/id/tax/income/deductions/id_deductions.py b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_deductions.py
index 460511569ae..d10534624fe 100644
--- a/policyengine_us/variables/gov/states/id/tax/income/deductions/id_deductions.py
+++ b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_deductions.py
@@ -16,5 +16,6 @@ class id_deductions(Variable):
     def formula(tax_unit, period, parameters):
         itm_ded = tax_unit("id_itemized_deductions", period)
         std_ded = tax_unit("standard_deduction", period)
-        # Idaho Form 40 line 18 deductions are modeled separately.
+        # Idaho qualified business income and federal Schedule 1-A deductions
+        # are modeled separately.
         return max_(itm_ded, std_ded)
diff --git a/policyengine_us/variables/gov/states/id/tax/income/deductions/id_line_18_deductions.py b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_qualified_business_income_and_federal_schedule_1a_deductions.py
similarity index 75%
rename from policyengine_us/variables/gov/states/id/tax/income/deductions/id_line_18_deductions.py
rename to policyengine_us/variables/gov/states/id/tax/income/deductions/id_qualified_business_income_and_federal_schedule_1a_deductions.py
index 1bec19e5e87..f3970a2c198 100644
--- a/policyengine_us/variables/gov/states/id/tax/income/deductions/id_line_18_deductions.py
+++ b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_qualified_business_income_and_federal_schedule_1a_deductions.py
@@ -1,10 +1,10 @@
 from policyengine_us.model_api import *
 
 
-class id_line_18_deductions(Variable):
+class id_qualified_business_income_and_federal_schedule_1a_deductions(Variable):
     value_type = float
     entity = TaxUnit
-    label = "Idaho Form 40 line 18 deductions"
+    label = "Idaho qualified business income and federal Schedule 1-A deductions"
     unit = USD
     definition_period = YEAR
     defined_for = StateCode.ID
diff --git a/policyengine_us/variables/gov/states/id/tax/income/id_taxable_income.py b/policyengine_us/variables/gov/states/id/tax/income/id_taxable_income.py
index b9a30edd777..a6b13b275d7 100644
--- a/policyengine_us/variables/gov/states/id/tax/income/id_taxable_income.py
+++ b/policyengine_us/variables/gov/states/id/tax/income/id_taxable_income.py
@@ -14,5 +14,8 @@ class id_taxable_income(Variable):
     def formula(tax_unit, period, parameters):
         agi = tax_unit("id_agi", period)
         deductions = tax_unit("id_deductions", period)
-        line_18_deductions = tax_unit("id_line_18_deductions", period)
-        return max_(0, agi - deductions - line_18_deductions)
+        conformity_deductions = tax_unit(
+            "id_qualified_business_income_and_federal_schedule_1a_deductions",
+            period,
+        )
+        return max_(0, agi - deductions - conformity_deductions)

From a233af22bdec583e81a2baf963b7a5b56dbba0ba Mon Sep 17 00:00:00 2001
From: PavelMakarchuk <pavel.ma99@gmail.com>
Date: Mon, 20 Apr 2026 00:00:31 -0400
Subject: [PATCH 4/7] Add pre-2025 zero values to federal senior deduction
 parameters

The senior deduction was introduced in 2025 by H.R.1 but the
parameters only had values from 2025-01-01, causing microsim
crashes when running for 2024. Add 2018-01-01 entries with 0
so the parameter tree is valid for all years.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 .../gov/irs/deductions/senior_deduction/amount.yaml         | 1 +
 .../deductions/senior_deduction/phase_out_rate/joint.yaml   | 6 ++++--
 .../deductions/senior_deduction/phase_out_rate/other.yaml   | 6 ++++--
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/policyengine_us/parameters/gov/irs/deductions/senior_deduction/amount.yaml b/policyengine_us/parameters/gov/irs/deductions/senior_deduction/amount.yaml
index 6df7370181a..54f82f86dd1 100644
--- a/policyengine_us/parameters/gov/irs/deductions/senior_deduction/amount.yaml
+++ b/policyengine_us/parameters/gov/irs/deductions/senior_deduction/amount.yaml
@@ -1,6 +1,7 @@
 description: The IRS provides a deduction for seniors of this amount.
 
 values:
+  2018-01-01: 0
   2025-01-01: 6_000
 
 metadata:
diff --git a/policyengine_us/parameters/gov/irs/deductions/senior_deduction/phase_out_rate/joint.yaml b/policyengine_us/parameters/gov/irs/deductions/senior_deduction/phase_out_rate/joint.yaml
index ee3af732f69..443ae86f8d3 100644
--- a/policyengine_us/parameters/gov/irs/deductions/senior_deduction/phase_out_rate/joint.yaml
+++ b/policyengine_us/parameters/gov/irs/deductions/senior_deduction/phase_out_rate/joint.yaml
@@ -11,10 +11,12 @@ metadata:
 
 brackets:
   - threshold:
-      2025-01-01: 0
+      2018-01-01: 0
     rate:
-      2025-01-01: 0
+      2018-01-01: 0
   - threshold:
+      2018-01-01: 150_000
       2025-01-01: 150_000
     rate:
+      2018-01-01: 0
       2025-01-01: 0.06
diff --git a/policyengine_us/parameters/gov/irs/deductions/senior_deduction/phase_out_rate/other.yaml b/policyengine_us/parameters/gov/irs/deductions/senior_deduction/phase_out_rate/other.yaml
index f254d8e63c4..1a4a410ac4a 100644
--- a/policyengine_us/parameters/gov/irs/deductions/senior_deduction/phase_out_rate/other.yaml
+++ b/policyengine_us/parameters/gov/irs/deductions/senior_deduction/phase_out_rate/other.yaml
@@ -11,10 +11,12 @@ metadata:
 
 brackets:
   - threshold:
-      2025-01-01: 0
+      2018-01-01: 0
     rate:
-      2025-01-01: 0
+      2018-01-01: 0
   - threshold:
+      2018-01-01: 75_000
       2025-01-01: 75_000
     rate:
+      2018-01-01: 0
       2025-01-01: 0.06

From 1286ce964ae7fd2cb1c9ea68e94b8b25d743ccba Mon Sep 17 00:00:00 2001
From: PavelMakarchuk <pavel.ma99@gmail.com>
Date: Mon, 20 Apr 2026 00:26:28 -0400
Subject: [PATCH 5/7] Fix review findings for Idaho senior deduction conformity

- Add missing Schedule 1-A deductions (tip, overtime, car loan
  interest) to id_qualified_business_income_and_federal_schedule_1a_deductions
- Add #page= anchors to PDF references
- Add permanent statute reference (IC 63-3004) to id_additional_senior_deduction
- Remove redundant documentation field from id_taxable_income
- Rename changelog from .fixed to .added (new functionality)
- Add test cases: pre-2025 zero, single filer phase-out, age
  boundary (64 vs 65), and full phase-out elimination

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 ....md => id-hb559-senior-deduction.added.md} |   0
 .../id_additional_senior_deduction.yaml       | 114 ++++++++++++++++++
 .../id_additional_senior_deduction.py         |   1 +
 ...come_and_federal_schedule_1a_deductions.py |   5 +-
 .../states/id/tax/income/id_taxable_income.py |   3 +-
 5 files changed, 120 insertions(+), 3 deletions(-)
 rename changelog.d/{id-hb559-senior-deduction.fixed.md => id-hb559-senior-deduction.added.md} (100%)

diff --git a/changelog.d/id-hb559-senior-deduction.fixed.md b/changelog.d/id-hb559-senior-deduction.added.md
similarity index 100%
rename from changelog.d/id-hb559-senior-deduction.fixed.md
rename to changelog.d/id-hb559-senior-deduction.added.md
diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml
index aaea6384373..b65d022bae4 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml
@@ -26,3 +26,117 @@
   output:
     additional_senior_deduction: 9_000
     id_additional_senior_deduction: 9_000
+
+- name: Idaho senior deduction is zero before 2025.
+  period: 2024
+  input:
+    people:
+      person1:
+        age: 70
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+        adjusted_gross_income: 50_000
+    households:
+      household:
+        members: [person1]
+        state_code: ID
+  output:
+    id_additional_senior_deduction: 0
+
+- name: Single filer senior deduction with non-joint phase-out
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 70
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+        adjusted_gross_income: 100_000
+        salt_deduction: 0
+        standard_deduction: 0
+    households:
+      household:
+        members: [person1]
+        state_code: ID
+  output:
+    # $6,000 base - 6% * ($100,000 - $75,000) = $6,000 - $1,500 = $4,500
+    id_additional_senior_deduction: 4_500
+
+- name: Age 64 does not qualify for senior deduction
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 64
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+        adjusted_gross_income: 50_000
+    households:
+      household:
+        members: [person1]
+        state_code: ID
+  output:
+    id_additional_senior_deduction: 0
+
+- name: Age 65 qualifies for senior deduction
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 65
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+        adjusted_gross_income: 50_000
+        salt_deduction: 0
+        standard_deduction: 0
+    households:
+      household:
+        members: [person1]
+        state_code: ID
+  output:
+    # Below $75k threshold, no phase-out
+    id_additional_senior_deduction: 6_000
+
+- name: Phase-out fully eliminates senior deduction
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 70
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+        adjusted_gross_income: 200_000
+        salt_deduction: 0
+        standard_deduction: 0
+    households:
+      household:
+        members: [person1]
+        state_code: ID
+  output:
+    # 6% * ($200,000 - $75,000) = $7,500 > $6,000, so capped at 0
+    id_additional_senior_deduction: 0
diff --git a/policyengine_us/variables/gov/states/id/tax/income/deductions/id_additional_senior_deduction.py b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_additional_senior_deduction.py
index bbbfb2a5572..227fe24e5dd 100644
--- a/policyengine_us/variables/gov/states/id/tax/income/deductions/id_additional_senior_deduction.py
+++ b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_additional_senior_deduction.py
@@ -9,6 +9,7 @@ class id_additional_senior_deduction(Variable):
     definition_period = YEAR
     defined_for = StateCode.ID
     reference = (
+        "https://legislature.idaho.gov/statutesrules/idstat/Title63/T63CH30/SECT63-3004/",
         "https://legislature.idaho.gov/sessioninfo/2026/legislation/H0559/",
         "https://tax.idaho.gov/pressrelease/update-on-filing-2025-idaho-income-taxes-now-that-conformity-is-law/",
     )
diff --git a/policyengine_us/variables/gov/states/id/tax/income/deductions/id_qualified_business_income_and_federal_schedule_1a_deductions.py b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_qualified_business_income_and_federal_schedule_1a_deductions.py
index f3970a2c198..4d24963a410 100644
--- a/policyengine_us/variables/gov/states/id/tax/income/deductions/id_qualified_business_income_and_federal_schedule_1a_deductions.py
+++ b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_qualified_business_income_and_federal_schedule_1a_deductions.py
@@ -9,11 +9,14 @@ class id_qualified_business_income_and_federal_schedule_1a_deductions(Variable):
     definition_period = YEAR
     defined_for = StateCode.ID
     reference = (
-        "https://tax.idaho.gov/wp-content/uploads/forms/EIN00046/EIN00046_03-02-2026.pdf",
+        "https://tax.idaho.gov/wp-content/uploads/forms/EIN00046/EIN00046_03-02-2026.pdf#page=11",
         "https://tax.idaho.gov/pressrelease/update-on-filing-2025-idaho-income-taxes-now-that-conformity-is-law/",
     )
 
     adds = [
         "qualified_business_income_deduction",
         "id_additional_senior_deduction",
+        "tip_income_deduction",
+        "overtime_income_deduction",
+        "auto_loan_interest_deduction",
     ]
diff --git a/policyengine_us/variables/gov/states/id/tax/income/id_taxable_income.py b/policyengine_us/variables/gov/states/id/tax/income/id_taxable_income.py
index a6b13b275d7..7674bd07552 100644
--- a/policyengine_us/variables/gov/states/id/tax/income/id_taxable_income.py
+++ b/policyengine_us/variables/gov/states/id/tax/income/id_taxable_income.py
@@ -6,9 +6,8 @@ class id_taxable_income(Variable):
     entity = TaxUnit
     label = "Idaho taxable income"
     unit = USD
-    documentation = "Idaho taxable income"
     definition_period = YEAR
-    reference = "https://tax.idaho.gov/wp-content/uploads/forms/EIN00046/EIN00046_03-02-2026.pdf"
+    reference = "https://tax.idaho.gov/wp-content/uploads/forms/EIN00046/EIN00046_03-02-2026.pdf#page=30"
     defined_for = StateCode.ID
 
     def formula(tax_unit, period, parameters):

From 8408075c9e76f8ae6c38db04e7a1495e4b739ae5 Mon Sep 17 00:00:00 2001
From: PavelMakarchuk <pavel.ma99@gmail.com>
Date: Tue, 21 Apr 2026 18:42:22 -0400
Subject: [PATCH 6/7] Update ID senior deduction tests for per-senior phase-out
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Main's federal additional_senior_deduction now applies the Schedule 1-A
phase-out per eligible senior before summing (commit f6fafc5afb). For
joint filers with both age 70 and AGI $200k, the correct value is $6,000
(2 × max($6k − $3k, 0)), not $9,000 as this branch originally expected.

Updates three tests to match the corrected federal formula:
- id_additional_senior_deduction.yaml joint case
- id_taxable_income.yaml conformity scalar input
- integration.yaml joint senior integration

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 .../income/deductions/id_additional_senior_deduction.yaml | 7 +++++--
 .../gov/states/id/tax/income/id_taxable_income.yaml       | 4 ++--
 .../baseline/gov/states/id/tax/income/integration.yaml    | 8 ++++----
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml
index b65d022bae4..0a85525c64d 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml
@@ -24,8 +24,11 @@
         members: [person1, person2]
         state_code: ID
   output:
-    additional_senior_deduction: 9_000
-    id_additional_senior_deduction: 9_000
+    # Joint, both age 70, AGI $200k: per-senior allowed is
+    # max($6,000 - 6% * ($200,000 - $150,000), 0) = $3,000,
+    # times 2 eligible seniors = $6,000 (Schedule 1-A per-senior phase-out).
+    additional_senior_deduction: 6_000
+    id_additional_senior_deduction: 6_000
 
 - name: Idaho senior deduction is zero before 2025.
   period: 2024
diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/id_taxable_income.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/id_taxable_income.yaml
index 882cb6a78d3..5589eb3bc4f 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/id_taxable_income.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/id_taxable_income.yaml
@@ -32,7 +32,7 @@
   input:
     id_agi: 200_000
     id_deductions: 60_000
-    id_qualified_business_income_and_federal_schedule_1a_deductions: 9_000
+    id_qualified_business_income_and_federal_schedule_1a_deductions: 6_000
     state_code: ID
   output:
-    id_taxable_income: 131_000
+    id_taxable_income: 134_000
diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml
index 12b4399c2fd..a96995acc78 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/integration.yaml
@@ -262,7 +262,7 @@
         members: [person1, person2]
         state_fips: 16
   output:
-    additional_senior_deduction: 9_000
-    id_additional_senior_deduction: 9_000
-    id_qualified_business_income_and_federal_schedule_1a_deductions: 9_000
-    id_taxable_income: 131_000
+    additional_senior_deduction: 6_000
+    id_additional_senior_deduction: 6_000
+    id_qualified_business_income_and_federal_schedule_1a_deductions: 6_000
+    id_taxable_income: 134_000

From cc196636661b0076e389e4b084761f6ba9a2c400 Mon Sep 17 00:00:00 2001
From: Ziming <ziming@policyengine.org>
Date: Sun, 26 Apr 2026 17:15:44 -0400
Subject: [PATCH 7/7] Use adds pattern + add phase-out boundary tests for ID
 senior deduction

- Replace formula wrapper with `adds = ["additional_senior_deduction"]`
  in id_additional_senior_deduction.py, matching the Indiana OBBBA
  conformity precedent and the sibling aggregator in this PR.
- Add boundary tests around the federal phase-out thresholds:
  single $74,999 / $75,000 / $75,001, joint $149,999 / $150,000 /
  $150,001, and joint full phase-out at $350,000.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 .../id_additional_senior_deduction.yaml       | 184 ++++++++++++++++++
 .../id_additional_senior_deduction.py         |   4 +-
 2 files changed, 185 insertions(+), 3 deletions(-)

diff --git a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml
index 0a85525c64d..0952a1cfd7f 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/id/tax/income/deductions/id_additional_senior_deduction.yaml
@@ -143,3 +143,187 @@
   output:
     # 6% * ($200,000 - $75,000) = $7,500 > $6,000, so capped at 0
     id_additional_senior_deduction: 0
+
+- name: Single filer just below $75,000 phase-out threshold.
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 70
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+        adjusted_gross_income: 74_999
+        salt_deduction: 0
+        standard_deduction: 0
+    households:
+      household:
+        members: [person1]
+        state_code: ID
+  output:
+    id_additional_senior_deduction: 6_000
+
+- name: Single filer at $75,000 phase-out threshold.
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 70
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+        adjusted_gross_income: 75_000
+        salt_deduction: 0
+        standard_deduction: 0
+    households:
+      household:
+        members: [person1]
+        state_code: ID
+  output:
+    id_additional_senior_deduction: 6_000
+
+- name: Single filer one dollar above $75,000 phase-out threshold.
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 70
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+        adjusted_gross_income: 75_001
+        salt_deduction: 0
+        standard_deduction: 0
+    households:
+      household:
+        members: [person1]
+        state_code: ID
+  output:
+    # max($6,000 - 6% * $1, 0) = $5,999.94
+    id_additional_senior_deduction: 5_999.94
+
+- name: Joint filer just below $150,000 phase-out threshold.
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 70
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+      person2:
+        age: 70
+        is_tax_unit_spouse: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+        adjusted_gross_income: 149_999
+        salt_deduction: 0
+        standard_deduction: 0
+    households:
+      household:
+        members: [person1, person2]
+        state_code: ID
+  output:
+    id_additional_senior_deduction: 12_000
+
+- name: Joint filer at $150,000 phase-out threshold.
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 70
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+      person2:
+        age: 70
+        is_tax_unit_spouse: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+        adjusted_gross_income: 150_000
+        salt_deduction: 0
+        standard_deduction: 0
+    households:
+      household:
+        members: [person1, person2]
+        state_code: ID
+  output:
+    id_additional_senior_deduction: 12_000
+
+- name: Joint filer one dollar above $150,000 phase-out threshold.
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 70
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+      person2:
+        age: 70
+        is_tax_unit_spouse: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+        adjusted_gross_income: 150_001
+        salt_deduction: 0
+        standard_deduction: 0
+    households:
+      household:
+        members: [person1, person2]
+        state_code: ID
+  output:
+    # Per senior: max($6,000 - 6% * $1, 0) = $5,999.94, times two seniors = $11,999.88.
+    id_additional_senior_deduction: 11_999.88
+
+- name: Joint filer fully phased out at $350,000 AGI.
+  period: 2025
+  input:
+    people:
+      person1:
+        age: 70
+        is_tax_unit_head: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+      person2:
+        age: 70
+        is_tax_unit_spouse: true
+        is_tax_unit_head_or_spouse: true
+        ssn_card_type: CITIZEN
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+        adjusted_gross_income: 350_000
+        salt_deduction: 0
+        standard_deduction: 0
+    households:
+      household:
+        members: [person1, person2]
+        state_code: ID
+  output:
+    # 6% * ($350,000 - $150,000) = $12,000 >= $6,000 per senior, so deduction is fully phased out.
+    id_additional_senior_deduction: 0
diff --git a/policyengine_us/variables/gov/states/id/tax/income/deductions/id_additional_senior_deduction.py b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_additional_senior_deduction.py
index 227fe24e5dd..02b95877619 100644
--- a/policyengine_us/variables/gov/states/id/tax/income/deductions/id_additional_senior_deduction.py
+++ b/policyengine_us/variables/gov/states/id/tax/income/deductions/id_additional_senior_deduction.py
@@ -13,6 +13,4 @@ class id_additional_senior_deduction(Variable):
         "https://legislature.idaho.gov/sessioninfo/2026/legislation/H0559/",
         "https://tax.idaho.gov/pressrelease/update-on-filing-2025-idaho-income-taxes-now-that-conformity-is-law/",
     )
-
-    def formula(tax_unit, period, parameters):
-        return tax_unit("additional_senior_deduction", period)
+    adds = ["additional_senior_deduction"]