Repository: PolicyEngine/policyengine-us (language: python)

Issue:
Kentucky Income Tax Rate 2024 (4.5% -> 4%)

![KY income tax](https://github.com/user-attachments/assets/38c221e6-b452-4659-88bd-ea17e9cc22fe)


[Reference](https://apps.legislature.ky.gov/law/statutes/statute.aspx?id=54585)



Discussion / hints:
https://github.com/PolicyEngine/policyengine-us/blob/7ba8021d14658eacb36912c7b4213ffcc6343a15/policyengine_us/parameters/gov/states/ky/tax/income/rate.yaml#L1-L5

Fix patch:
diff --git a/changelog_entry.yaml b/changelog_entry.yaml
index e69de29bb2d..8e4fc78f8a5 100644
--- a/changelog_entry.yaml
+++ b/changelog_entry.yaml
@@ -0,0 +1,4 @@
+- bump: minor
+  changes:
+    added: 
+    - 2024 Kentucky income tax rate reduction.
diff --git a/policyengine_us/parameters/gov/states/ky/tax/income/rate.yaml b/policyengine_us/parameters/gov/states/ky/tax/income/rate.yaml
index 191e6bcb6ce..290b3db33ca 100644
--- a/policyengine_us/parameters/gov/states/ky/tax/income/rate.yaml
+++ b/policyengine_us/parameters/gov/states/ky/tax/income/rate.yaml
@@ -2,15 +2,18 @@ description: Kentucky taxes individual income at this rate.
 values:
   2021-01-01: 0.05
   2023-01-01: 0.045
+  2024-01-01: 0.04
 metadata:
   unit: /1
   label: Kentucky income tax rate
   reference:
-    - title: Kentucky Individual Income Tax Return Residents Only - Form 740 - Line 12
+    - title: 2021 Kentucky Individual Income Tax Return Residents Only - Form 740 - Line 12
       href: https://revenue.ky.gov/Forms/Form%20740-2021.pdf#page=1
-    - title: Kentucky Department of Revenue
+    - title: 2023 Kentucky Department of Revenue
       href: https://revenue.ky.gov/News/Pages/DOR-Announces-Updates-to-Individual-Income-Tax-for-2023-Tax-Year.aspx
-    - title: Kentucky Individual Income Tax Return Residents Only - Form 740
+    - title: 2023 Kentucky Individual Income Tax Return Residents Only - Form 740
       href: https://revenue.ky.gov/Forms/Form%20740%205-9-23.pdf#page=1
-    - title: Kentucky Estimated Tax Voucher Instructions
+    - title: 2023 Kentucky Estimated Tax Voucher Instructions
       href: https://revenue.ky.gov/Forms/740-ES%20Instructions%203-21-23.pdf
+    - title: Kentucky Statutes 141.020
+      href: https://apps.legislature.ky.gov/law/statutes/statute.aspx?id=54585


Test patch:
diff --git a/policyengine_us/tests/policy/baseline/gov/states/ky/tax/income/ky_income_tax_before_non_refundable_credits_indiv.yaml b/policyengine_us/tests/policy/baseline/gov/states/ky/tax/income/ky_income_tax_before_non_refundable_credits_indiv.yaml
index a59ae585bbe..42f884b67bd 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/ky/tax/income/ky_income_tax_before_non_refundable_credits_indiv.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/ky/tax/income/ky_income_tax_before_non_refundable_credits_indiv.yaml
@@ -14,3 +14,10 @@
   output:
     ky_income_tax_before_non_refundable_credits_indiv: 4.5
 
+- name: 2024, separate
+  period: 2024
+  input:
+    ky_taxable_income_indiv: 100
+    state_code: KY
+  output:
+    ky_income_tax_before_non_refundable_credits_indiv: 4
diff --git a/policyengine_us/tests/policy/baseline/gov/states/ky/tax/income/ky_income_tax_before_non_refundable_credits_joint.yaml b/policyengine_us/tests/policy/baseline/gov/states/ky/tax/income/ky_income_tax_before_non_refundable_credits_joint.yaml
index e7dd43f432b..48e71f7c71c 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/ky/tax/income/ky_income_tax_before_non_refundable_credits_joint.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/ky/tax/income/ky_income_tax_before_non_refundable_credits_joint.yaml
@@ -14,3 +14,10 @@
   output:
     ky_income_tax_before_non_refundable_credits_joint: 4.5
 
+- name: 2024, joint
+  period: 2024
+  input:
+    ky_taxable_income_joint: 100
+    state_code: KY
+  output:
+    ky_income_tax_before_non_refundable_credits_joint: 4
diff --git a/policyengine_us/tests/policy/baseline/gov/states/ky/tax/income/ky_income_tax_before_non_refundable_credits_unit.yaml b/policyengine_us/tests/policy/baseline/gov/states/ky/tax/income/ky_income_tax_before_non_refundable_credits_unit.yaml
index 6f4ec2fef7b..4df46505824 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/ky/tax/income/ky_income_tax_before_non_refundable_credits_unit.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/ky/tax/income/ky_income_tax_before_non_refundable_credits_unit.yaml
@@ -27,3 +27,13 @@
     state_code: KY
   output:
     ky_income_tax_before_non_refundable_credits_unit: 9
+
+- name: 2024, joint
+  period: 2024
+  input:
+    ky_files_separately: false
+    ky_taxable_income_indiv: 100
+    ky_taxable_income_joint: 200
+    state_code: KY
+  output:
+    ky_income_tax_before_non_refundable_credits_unit: 8