diff --git a/changelog.d/ky-hb13-hb152-graduated-income-tax.added.md b/changelog.d/ky-hb13-hb152-graduated-income-tax.added.md
new file mode 100644
index 00000000000..fb7303785c2
--- /dev/null
+++ b/changelog.d/ky-hb13-hb152-graduated-income-tax.added.md
@@ -0,0 +1 @@
+Added Kentucky HB 13 and HB 152 graduated income tax reforms with cliff design.
diff --git a/policyengine_us/parameters/gov/contrib/states/ky/hb13/brackets.yaml b/policyengine_us/parameters/gov/contrib/states/ky/hb13/brackets.yaml
new file mode 100644
index 00000000000..063bc2876b2
--- /dev/null
+++ b/policyengine_us/parameters/gov/contrib/states/ky/hb13/brackets.yaml
@@ -0,0 +1,21 @@
+description: Kentucky HB 13 graduated income tax brackets for income at or below the cliff threshold.
+
+metadata:
+  type: marginal_rate
+  threshold_unit: currency-USD
+  rate_unit: /1
+  period: year
+  label: Kentucky HB 13 graduated income tax brackets
+  reference:
+    - title: Kentucky HB 13 (2026 Session), Section 1, KRS 141.020(2)
+      href: https://apps.legislature.ky.gov/recorddocuments/bill/26RS/hb13/orig_bill.pdf#page=1
+
+brackets:
+  - threshold:
+      2027-01-01: 0
+    rate:
+      2027-01-01: 0.035
+  - threshold:
+      2027-01-01: 250_000
+    rate:
+      2027-01-01: 0.06
diff --git a/policyengine_us/parameters/gov/contrib/states/ky/hb13/cliff_threshold.yaml b/policyengine_us/parameters/gov/contrib/states/ky/hb13/cliff_threshold.yaml
new file mode 100644
index 00000000000..42ab7c9252d
--- /dev/null
+++ b/policyengine_us/parameters/gov/contrib/states/ky/hb13/cliff_threshold.yaml
@@ -0,0 +1,12 @@
+description: Kentucky House Bill 13 sets this as the income threshold above which the flat rate applies to the entire income.
+
+values:
+  2027-01-01: 300_000
+
+metadata:
+  unit: currency-USD
+  period: year
+  label: Kentucky HB 13 cliff threshold
+  reference:
+    - title: Kentucky HB 13 (2026 Session), Section 1, KRS 141.020(2)
+      href: https://apps.legislature.ky.gov/recorddocuments/bill/26RS/hb13/orig_bill.pdf#page=1
diff --git a/policyengine_us/parameters/gov/contrib/states/ky/hb13/flat_rate.yaml b/policyengine_us/parameters/gov/contrib/states/ky/hb13/flat_rate.yaml
new file mode 100644
index 00000000000..565d34adbf8
--- /dev/null
+++ b/policyengine_us/parameters/gov/contrib/states/ky/hb13/flat_rate.yaml
@@ -0,0 +1,12 @@
+description: Kentucky HB 13 flat rate applied to entire income when income exceeds the cliff threshold.
+
+values:
+  2027-01-01: 0.06
+
+metadata:
+  unit: /1
+  period: year
+  label: Kentucky HB 13 flat rate for high earners
+  reference:
+    - title: Kentucky HB 13 (2026 Session), Section 1, KRS 141.020(2)
+      href: https://apps.legislature.ky.gov/recorddocuments/bill/26RS/hb13/orig_bill.pdf#page=1
diff --git a/policyengine_us/parameters/gov/contrib/states/ky/hb13/in_effect.yaml b/policyengine_us/parameters/gov/contrib/states/ky/hb13/in_effect.yaml
new file mode 100644
index 00000000000..a611f80d1eb
--- /dev/null
+++ b/policyengine_us/parameters/gov/contrib/states/ky/hb13/in_effect.yaml
@@ -0,0 +1,14 @@
+description: Whether Kentucky HB 13 graduated income tax reform is in effect.
+
+values:
+  0000-01-01: false
+
+metadata:
+  unit: bool
+  label: Kentucky HB 13 graduated income tax reform in effect
+  period: year
+  reference:
+    - title: Kentucky HB 13 (2026 Session), Section 1, KRS 141.020(2)
+      href: https://apps.legislature.ky.gov/recorddocuments/bill/26RS/hb13/orig_bill.pdf#page=1
+    - title: Kentucky Legislature - HB 13 (bill status)
+      href: https://apps.legislature.ky.gov/record/26RS/hb13.html
diff --git a/policyengine_us/parameters/gov/contrib/states/ky/hb152/brackets.yaml b/policyengine_us/parameters/gov/contrib/states/ky/hb152/brackets.yaml
new file mode 100644
index 00000000000..d9ec745e6c1
--- /dev/null
+++ b/policyengine_us/parameters/gov/contrib/states/ky/hb152/brackets.yaml
@@ -0,0 +1,25 @@
+description: Kentucky HB 152 graduated income tax brackets for income at or below the cliff threshold.
+
+metadata:
+  type: marginal_rate
+  threshold_unit: currency-USD
+  rate_unit: /1
+  period: year
+  label: Kentucky HB 152 graduated income tax brackets
+  reference:
+    - title: Kentucky HB 152 (2026 Session), Section 1, KRS 141.020(2)
+      href: https://apps.legislature.ky.gov/recorddocuments/bill/26RS/hb152/orig_bill.pdf#page=1
+
+brackets:
+  - threshold:
+      2027-01-01: 0
+    rate:
+      2027-01-01: 0.04
+  - threshold:
+      2027-01-01: 100_000
+    rate:
+      2027-01-01: 0.05
+  - threshold:
+      2027-01-01: 125_000
+    rate:
+      2027-01-01: 0.06
diff --git a/policyengine_us/parameters/gov/contrib/states/ky/hb152/cliff_threshold.yaml b/policyengine_us/parameters/gov/contrib/states/ky/hb152/cliff_threshold.yaml
new file mode 100644
index 00000000000..f745143fbb0
--- /dev/null
+++ b/policyengine_us/parameters/gov/contrib/states/ky/hb152/cliff_threshold.yaml
@@ -0,0 +1,12 @@
+description: Kentucky House Bill 152 sets this as the income threshold at or above which the flat rate applies to the entire income.
+
+values:
+  2027-01-01: 150_000
+
+metadata:
+  unit: currency-USD
+  period: year
+  label: Kentucky HB 152 cliff threshold
+  reference:
+    - title: Kentucky HB 152 (2026 Session), Section 1, KRS 141.020(2)
+      href: https://apps.legislature.ky.gov/recorddocuments/bill/26RS/hb152/orig_bill.pdf#page=1
diff --git a/policyengine_us/parameters/gov/contrib/states/ky/hb152/flat_rate.yaml b/policyengine_us/parameters/gov/contrib/states/ky/hb152/flat_rate.yaml
new file mode 100644
index 00000000000..c972cd3356b
--- /dev/null
+++ b/policyengine_us/parameters/gov/contrib/states/ky/hb152/flat_rate.yaml
@@ -0,0 +1,12 @@
+description: Kentucky HB 152 flat rate applied to entire income when income exceeds the cliff threshold.
+
+values:
+  2027-01-01: 0.06
+
+metadata:
+  unit: /1
+  period: year
+  label: Kentucky HB 152 flat rate for high earners
+  reference:
+    - title: Kentucky HB 152 (2026 Session), Section 1, KRS 141.020(2)
+      href: https://apps.legislature.ky.gov/recorddocuments/bill/26RS/hb152/orig_bill.pdf#page=1
diff --git a/policyengine_us/parameters/gov/contrib/states/ky/hb152/in_effect.yaml b/policyengine_us/parameters/gov/contrib/states/ky/hb152/in_effect.yaml
new file mode 100644
index 00000000000..fe86c43e10e
--- /dev/null
+++ b/policyengine_us/parameters/gov/contrib/states/ky/hb152/in_effect.yaml
@@ -0,0 +1,14 @@
+description: Whether Kentucky HB 152 graduated income tax reform is in effect.
+
+values:
+  0000-01-01: false
+
+metadata:
+  unit: bool
+  label: Kentucky HB 152 graduated income tax reform in effect
+  period: year
+  reference:
+    - title: Kentucky HB 152 (2026 Session), Section 1, KRS 141.020(2)
+      href: https://apps.legislature.ky.gov/recorddocuments/bill/26RS/hb152/orig_bill.pdf#page=1
+    - title: Kentucky Legislature - HB 152 (bill status)
+      href: https://apps.legislature.ky.gov/record/26RS/hb152.html
diff --git a/policyengine_us/reforms/reforms.py b/policyengine_us/reforms/reforms.py
index 8cf12ebddbc..31a4b214efc 100644
--- a/policyengine_us/reforms/reforms.py
+++ b/policyengine_us/reforms/reforms.py
@@ -151,6 +151,9 @@
 from .cdcc import (
     create_cdcc_single_parent_work_requirement_reform,
 )
+from .states.ky.graduated_income_tax import (
+    create_ky_graduated_income_tax_reform,
+)
 from .states.pa.ctc import (
     create_pa_ctc_flat_amount_reform,
     create_pa_ctc_match_reform,
@@ -355,6 +358,9 @@ def create_structural_reforms_from_parameters(parameters, period):
     cdcc_single_parent_work_requirement = (
         create_cdcc_single_parent_work_requirement_reform(parameters, period)
     )
+    ky_graduated_income_tax = create_ky_graduated_income_tax_reform(
+        parameters, period
+    )
     pa_ctc_flat_amount = create_pa_ctc_flat_amount_reform(parameters, period)
     pa_ctc_match = create_pa_ctc_match_reform(parameters, period)
     ct_sb100 = create_ct_sb100_reform(parameters, period)
@@ -431,6 +437,7 @@ def create_structural_reforms_from_parameters(parameters, period):
         aca_ptc_simplified_bracket,
         aca_ptc_700_fpl_cliff,
         cdcc_single_parent_work_requirement,
+        ky_graduated_income_tax,
         pa_ctc_flat_amount,
         pa_ctc_match,
         ct_hb5009,
diff --git a/policyengine_us/reforms/states/ky/__init__.py b/policyengine_us/reforms/states/ky/__init__.py
new file mode 100644
index 00000000000..78ded887d71
--- /dev/null
+++ b/policyengine_us/reforms/states/ky/__init__.py
@@ -0,0 +1,4 @@
+from policyengine_us.reforms.states.ky.graduated_income_tax import (
+    create_ky_graduated_income_tax_reform,
+    ky_graduated_income_tax,
+)
diff --git a/policyengine_us/reforms/states/ky/graduated_income_tax/__init__.py b/policyengine_us/reforms/states/ky/graduated_income_tax/__init__.py
new file mode 100644
index 00000000000..a035175d9df
--- /dev/null
+++ b/policyengine_us/reforms/states/ky/graduated_income_tax/__init__.py
@@ -0,0 +1,4 @@
+from policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform import (
+    create_ky_graduated_income_tax_reform,
+    ky_graduated_income_tax,
+)
diff --git a/policyengine_us/reforms/states/ky/graduated_income_tax/ky_graduated_income_tax_reform.py b/policyengine_us/reforms/states/ky/graduated_income_tax/ky_graduated_income_tax_reform.py
new file mode 100644
index 00000000000..5996b03bc57
--- /dev/null
+++ b/policyengine_us/reforms/states/ky/graduated_income_tax/ky_graduated_income_tax_reform.py
@@ -0,0 +1,141 @@
+from policyengine_us.model_api import *
+from policyengine_core.periods import period as period_
+
+
+def create_ky_graduated_income_tax() -> Reform:
+    """
+    Creates reform for Kentucky HB 13 and HB 152 graduated income tax.
+
+    Both bills amend KRS 141.020(2) to implement graduated brackets
+    with a "cliff" design where above a threshold, the flat rate
+    applies to the ENTIRE income (not just marginal).
+
+    See parameter files under gov/contrib/states/ky/hb13/ and hb152/
+    for specific rates, thresholds, and effective dates.
+    """
+
+    def calculate_graduated_tax_with_cliff(
+        taxable_income, p_hb13, p_hb152, p_baseline
+    ):
+        """
+        Calculate tax using graduated brackets with cliff design.
+
+        HB 13 takes precedence if both are active. Each bill applies
+        its flat rate to the entire income when the cliff threshold
+        is exceeded; otherwise graduated brackets apply.
+        """
+        hb13_active = p_hb13.in_effect
+        hb152_active = p_hb152.in_effect
+
+        # HB 13 calculation
+        hb13_above_cliff = taxable_income > p_hb13.cliff_threshold
+        hb13_graduated_tax = p_hb13.brackets.calc(taxable_income)
+        hb13_flat_tax = taxable_income * p_hb13.flat_rate
+        hb13_tax = where(hb13_above_cliff, hb13_flat_tax, hb13_graduated_tax)
+
+        # HB 152 calculation
+        hb152_above_cliff = taxable_income >= p_hb152.cliff_threshold
+        hb152_graduated_tax = p_hb152.brackets.calc(taxable_income)
+        hb152_flat_tax = taxable_income * p_hb152.flat_rate
+        hb152_tax = where(
+            hb152_above_cliff, hb152_flat_tax, hb152_graduated_tax
+        )
+
+        # Baseline calculation
+        baseline_tax = taxable_income * p_baseline.rate
+
+        # Apply appropriate calculation based on which reform is active
+        # HB 13 takes precedence if both are somehow active
+        return where(
+            hb13_active,
+            hb13_tax,
+            where(hb152_active, hb152_tax, baseline_tax),
+        )
+
+    class ky_income_tax_before_non_refundable_credits_indiv(Variable):
+        value_type = float
+        entity = Person
+        label = "Kentucky income tax before non-refundable credits when married couples are filing separately"
+        unit = USD
+        definition_period = YEAR
+        defined_for = StateCode.KY
+        reference = (
+            "https://apps.legislature.ky.gov/recorddocuments/bill/26RS/hb13/orig_bill.pdf#page=1",
+            "https://apps.legislature.ky.gov/recorddocuments/bill/26RS/hb152/orig_bill.pdf#page=1",
+        )
+
+        def formula(person, period, parameters):
+            taxable_income = person("ky_taxable_income_indiv", period)
+            p_hb13 = parameters(period).gov.contrib.states.ky.hb13
+            p_hb152 = parameters(period).gov.contrib.states.ky.hb152
+            p_baseline = parameters(period).gov.states.ky.tax.income
+
+            return calculate_graduated_tax_with_cliff(
+                taxable_income, p_hb13, p_hb152, p_baseline
+            )
+
+    class ky_income_tax_before_non_refundable_credits_joint(Variable):
+        value_type = float
+        entity = Person
+        label = "Kentucky income tax before non-refundable credits when married filing jointly"
+        unit = USD
+        definition_period = YEAR
+        defined_for = StateCode.KY
+        reference = (
+            "https://apps.legislature.ky.gov/recorddocuments/bill/26RS/hb13/orig_bill.pdf#page=1",
+            "https://apps.legislature.ky.gov/recorddocuments/bill/26RS/hb152/orig_bill.pdf#page=1",
+        )
+
+        def formula(person, period, parameters):
+            taxable_income = person("ky_taxable_income_joint", period)
+            p_hb13 = parameters(period).gov.contrib.states.ky.hb13
+            p_hb152 = parameters(period).gov.contrib.states.ky.hb152
+            p_baseline = parameters(period).gov.states.ky.tax.income
+
+            return calculate_graduated_tax_with_cliff(
+                taxable_income, p_hb13, p_hb152, p_baseline
+            )
+
+    class reform(Reform):
+        def apply(self):
+            self.update_variable(
+                ky_income_tax_before_non_refundable_credits_indiv
+            )
+            self.update_variable(
+                ky_income_tax_before_non_refundable_credits_joint
+            )
+
+    return reform
+
+
+def create_ky_graduated_income_tax_reform(
+    parameters, period, bypass: bool = False
+):
+    if bypass:
+        return create_ky_graduated_income_tax()
+
+    p_hb13 = parameters.gov.contrib.states.ky.hb13
+    p_hb152 = parameters.gov.contrib.states.ky.hb152
+
+    reform_active = False
+    current_period = period_(period)
+
+    # Check if either reform will be active in the next 5 years
+    for i in range(5):
+        if (
+            p_hb13(current_period).in_effect
+            or p_hb152(current_period).in_effect
+        ):
+            reform_active = True
+            break
+        current_period = current_period.offset(1, "year")
+
+    if reform_active:
+        return create_ky_graduated_income_tax()
+    else:
+        return None
+
+
+ky_graduated_income_tax = create_ky_graduated_income_tax_reform(
+    None, None, bypass=True
+)
diff --git a/policyengine_us/tests/policy/contrib/states/ky/hb13/ky_hb13.yaml b/policyengine_us/tests/policy/contrib/states/ky/hb13/ky_hb13.yaml
new file mode 100644
index 00000000000..8c5b544db1b
--- /dev/null
+++ b/policyengine_us/tests/policy/contrib/states/ky/hb13/ky_hb13.yaml
@@ -0,0 +1,415 @@
+# Test Kentucky HB 13 Graduated Income Tax Reform
+# For 2027+: 3.5% up to $250k, 6% $250k-$300k, flat 6% on ALL income if >$300k
+
+- name: KY HB 13 - income below $250k threshold (single filing)
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 100_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # 100000 * 0.035 = 3500
+    ky_income_tax_before_non_refundable_credits_indiv: 3500
+
+- name: KY HB 13 - income between $250k and $300k (graduated rates)
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 280_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # 250000 * 0.035 + 30000 * 0.06 = 8750 + 1800 = 10550
+    ky_income_tax_before_non_refundable_credits_indiv: 10550
+
+- name: KY HB 13 - income at exactly $300k threshold (still graduated)
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 300_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # 250000 * 0.035 + 50000 * 0.06 = 8750 + 3000 = 11750
+    ky_income_tax_before_non_refundable_credits_indiv: 11750
+
+- name: KY HB 13 - income above $300k (cliff - flat 6% on ENTIRE income)
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 300_001
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # CLIFF: 300001 * 0.06 = 18000.06
+    ky_income_tax_before_non_refundable_credits_indiv: 18000.06
+
+- name: KY HB 13 - high income above cliff
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 500_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # CLIFF: 500000 * 0.06 = 30000
+    ky_income_tax_before_non_refundable_credits_indiv: 30000
+
+- name: KY HB 13 - joint filing above cliff
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_joint: 400_000
+      person2:
+        age: 43
+        ky_taxable_income_joint: 0
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: KY
+  output:
+    # CLIFF: 400000 * 0.06 = 24000 (on person1 who has the income)
+    ky_income_tax_before_non_refundable_credits_joint:
+      - 24000
+      - 0
+
+- name: KY HB 13 - reform not in effect uses baseline
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: false
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 500_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # Baseline 2027 rate: 3.5% -> 500000 * 0.035 = 17500
+    ky_income_tax_before_non_refundable_credits_indiv: 17500
+
+- name: KY HB 13 - zero income
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 0
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    ky_income_tax_before_non_refundable_credits_indiv: 0
+
+- name: KY HB 13 - income at exactly $250k bracket boundary
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 250_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # 250000 * 0.035 = 8750
+    ky_income_tax_before_non_refundable_credits_indiv: 8750
+
+- name: KY HB 13 - cliff notch just below $300k
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 299_999
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # Just below cliff: 250000*0.035 + 49999*0.06 = 8750 + 2999.94 = 11749.94
+    ky_income_tax_before_non_refundable_credits_indiv: 11749.94
+
+- name: KY HB 13 - both reforms active (HB 13 takes precedence)
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 200_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # HB 13 takes precedence: 200000 * 0.035 = 7000
+    # (HB 152 would give: 100000*0.04 + 25000*0.05 + 25000*0.06 + 50000*0.06 = 4000+1250+1500+3000 = 9750)
+    ky_income_tax_before_non_refundable_credits_indiv: 7000
+
+- name: KY HB 13 - non-KY resident gets zero
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 500_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: CA
+  output:
+    ky_income_tax_before_non_refundable_credits_indiv: 0
+
+- name: KY HB 13 - joint filing with graduated rates
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_joint: 280_000
+      person2:
+        age: 43
+        ky_taxable_income_joint: 0
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: KY
+  output:
+    # 250000*0.035 + 30000*0.06 = 8750 + 1800 = 10550
+    ky_income_tax_before_non_refundable_credits_joint:
+      - 10550
+      - 0
+
+- name: KY HB 13 - joint filing at exactly $300k cliff (still graduated)
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_joint: 300_000
+      person2:
+        age: 43
+        ky_taxable_income_joint: 0
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: KY
+  output:
+    # At $300k exactly, strict > means graduated rates apply
+    # 250000*0.035 + 50000*0.06 = 8750 + 3000 = 11750
+    ky_income_tax_before_non_refundable_credits_joint:
+      - 11750
+      - 0
+
+- name: KY HB 13 - joint filing $1 above cliff (flat 6% on entire income)
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_joint: 300_001
+      person2:
+        age: 43
+        ky_taxable_income_joint: 0
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: KY
+  output:
+    # CLIFF: 300001 * 0.06 = 18000.06
+    ky_income_tax_before_non_refundable_credits_joint:
+      - 18000.06
+      - 0
+
+- name: KY HB 13 - end-to-end high earner through ky_income_tax
+  period: 2027
+  absolute_error_margin: 1
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 500_000
+        ky_taxable_income_joint: 500_000
+      person2:
+        age: 43
+        ky_taxable_income_indiv: 0
+        ky_taxable_income_joint: 0
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+        adjusted_gross_income: 500_000
+    households:
+      household:
+        members: [person1, person2]
+        state_code: KY
+  output:
+    # CLIFF: 500000 * 0.06 = 30000
+    ky_income_tax_before_non_refundable_credits_joint:
+      - 30000
+      - 0
+    # High earner: family size credit rate is 0%, so no credit reduction
+    # Verify reform flows through to final ky_income_tax
+    ky_income_tax: 30000
+
+- name: KY HB 13 - filing optimization chooses separate filing
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 280_000
+        ky_taxable_income_joint: 300_000
+      person2:
+        age: 43
+        ky_taxable_income_indiv: 20_000
+        ky_taxable_income_joint: 0
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: KY
+  output:
+    # Separate: p1=250k*3.5%+30k*6%=10550, p2=20k*3.5%=700, total=11250
+    # Joint: p1=250k*3.5%+50k*6%=11750, p2=0, total=11750
+    # ky_files_separately = (11250 < 11750) = True
+    ky_files_separately: true
diff --git a/policyengine_us/tests/policy/contrib/states/ky/hb152/ky_hb152.yaml b/policyengine_us/tests/policy/contrib/states/ky/hb152/ky_hb152.yaml
new file mode 100644
index 00000000000..7fb8909709a
--- /dev/null
+++ b/policyengine_us/tests/policy/contrib/states/ky/hb152/ky_hb152.yaml
@@ -0,0 +1,429 @@
+# Test Kentucky HB 152 Graduated Income Tax Reform
+# For 2027+: 4% up to $100k, 5% $100k-$125k, 6% $125k-$150k,
+# flat 6% on ALL income if >= $150k
+
+- name: KY HB 152 - income below $100k threshold
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 50_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # 50000 * 0.04 = 2000
+    ky_income_tax_before_non_refundable_credits_indiv: 2000
+
+- name: KY HB 152 - income between $100k and $125k
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 110_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # 100000 * 0.04 + 10000 * 0.05 = 4000 + 500 = 4500
+    ky_income_tax_before_non_refundable_credits_indiv: 4500
+
+- name: KY HB 152 - income between $125k and $150k
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 140_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # 100000 * 0.04 + 25000 * 0.05 + 15000 * 0.06 = 4000 + 1250 + 900 = 6150
+    ky_income_tax_before_non_refundable_credits_indiv: 6150
+
+- name: KY HB 152 - income at exactly $150k threshold (cliff - flat 6%)
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 150_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # Bill says "$150,000 or more" triggers flat rate: 150000 * 0.06 = 9000
+    ky_income_tax_before_non_refundable_credits_indiv: 9000
+
+- name: KY HB 152 - income above $150k (cliff - flat 6% on ENTIRE income)
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 150_001
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # CLIFF: 150001 * 0.06 = 9000.06
+    ky_income_tax_before_non_refundable_credits_indiv: 9000.06
+
+- name: KY HB 152 - high income above cliff
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 300_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # CLIFF: 300000 * 0.06 = 18000
+    ky_income_tax_before_non_refundable_credits_indiv: 18000
+
+- name: KY HB 152 - joint filing above cliff
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_joint: 200_000
+      person2:
+        age: 43
+        ky_taxable_income_joint: 0
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: KY
+  output:
+    # CLIFF: 200000 * 0.06 = 12000 (on person1)
+    ky_income_tax_before_non_refundable_credits_joint:
+      - 12000
+      - 0
+
+- name: KY HB 152 - reform not in effect uses baseline
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: false
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 200_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # Baseline 2027 rate: 3.5% -> 200000 * 0.035 = 7000
+    ky_income_tax_before_non_refundable_credits_indiv: 7000
+
+- name: KY HB 152 - cliff notch effect demonstration
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 149_999
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # Just below cliff: 100000*0.04 + 25000*0.05 + 24999*0.06 = 4000+1250+1499.94 = 6749.94
+    ky_income_tax_before_non_refundable_credits_indiv: 6749.94
+
+- name: KY HB 152 - zero income
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 0
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    ky_income_tax_before_non_refundable_credits_indiv: 0
+
+- name: KY HB 152 - income at exactly $100k bracket boundary
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 100_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # 100000 * 0.04 = 4000
+    ky_income_tax_before_non_refundable_credits_indiv: 4000
+
+- name: KY HB 152 - income at exactly $125k bracket boundary
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 125_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # 100000 * 0.04 + 25000 * 0.05 = 4000 + 1250 = 5250
+    ky_income_tax_before_non_refundable_credits_indiv: 5250
+
+- name: KY HB 152 - non-KY resident gets zero
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 300_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: CA
+  output:
+    ky_income_tax_before_non_refundable_credits_indiv: 0
+
+- name: KY HB 152 - joint filing with graduated rates
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_joint: 140_000
+      person2:
+        age: 43
+        ky_taxable_income_joint: 0
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: KY
+  output:
+    # 100000*0.04 + 25000*0.05 + 15000*0.06 = 4000 + 1250 + 900 = 6150
+    ky_income_tax_before_non_refundable_credits_joint:
+      - 6150
+      - 0
+
+- name: KY HB 152 - joint filing $1 below cliff (graduated)
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_joint: 149_999
+      person2:
+        age: 43
+        ky_taxable_income_joint: 0
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: KY
+  output:
+    # Just below cliff: 100000*0.04 + 25000*0.05 + 24999*0.06 = 4000+1250+1499.94 = 6749.94
+    ky_income_tax_before_non_refundable_credits_joint:
+      - 6749.94
+      - 0
+
+- name: KY HB 152 - joint filing at exactly $150k cliff (flat 6%)
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_joint: 150_000
+      person2:
+        age: 43
+        ky_taxable_income_joint: 0
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+    households:
+      household:
+        members: [person1, person2]
+        state_code: KY
+  output:
+    # Bill says "$150,000 or more" triggers flat rate: 150000 * 0.06 = 9000
+    ky_income_tax_before_non_refundable_credits_joint:
+      - 9000
+      - 0
+
+- name: KY HB 152 - end-to-end high earner through ky_income_tax
+  period: 2027
+  absolute_error_margin: 1
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 300_000
+        ky_taxable_income_joint: 300_000
+      person2:
+        age: 43
+        ky_taxable_income_indiv: 0
+        ky_taxable_income_joint: 0
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        filing_status: JOINT
+        adjusted_gross_income: 300_000
+    households:
+      household:
+        members: [person1, person2]
+        state_code: KY
+  output:
+    # CLIFF: 300000 * 0.06 = 18000
+    ky_income_tax_before_non_refundable_credits_joint:
+      - 18000
+      - 0
+    # High earner: family size credit rate is 0%, so no credit reduction
+    # Verify reform flows through to final ky_income_tax
+    ky_income_tax: 18000
+
+- name: KY HB 152 - both reforms active (HB 13 takes precedence)
+  period: 2027
+  absolute_error_margin: 0.01
+  reforms: policyengine_us.reforms.states.ky.graduated_income_tax.ky_graduated_income_tax_reform.ky_graduated_income_tax
+  input:
+    gov.contrib.states.ky.hb13.in_effect: true
+    gov.contrib.states.ky.hb152.in_effect: true
+    people:
+      person1:
+        age: 45
+        ky_taxable_income_indiv: 200_000
+    tax_units:
+      tax_unit:
+        members: [person1]
+        filing_status: SINGLE
+    households:
+      household:
+        members: [person1]
+        state_code: KY
+  output:
+    # HB 13 takes precedence: 200000 * 0.035 = 7000
+    ky_income_tax_before_non_refundable_credits_indiv: 7000