Mamdani Millionaire Income Tax

changelog_entry.yaml

@@ -0,0 +1,4 @@
+- bump: minor
+  changes:
+    added:
+    - Mamdani Millionaire Income Tax.

policyengine_us/parameters/gov/local/ny/mamdani_income_tax/in_effect.yaml

@@ -0,0 +1,10 @@
+description: Zohran Mamdani's proposed additional NYC income tax on income above a certain threshold is in effect if this is true.
+values:
+  0000-01-01: false
+metadata:
+  unit: bool
+  period: year
+  label: Zohran Mamdani NYC additional millionaire income tax in effect
+  reference: 
+    - title: Mamdani Revenue Proposal
+      href: https://drive.google.com/file/d/14-aM9DKG337SDMilmfQtLRR-pDwyWSTc/view

policyengine_us/parameters/gov/local/ny/mamdani_income_tax/rate.yaml

@@ -0,0 +1,10 @@
+description: Zohran Mamdani's proposed this NYC income tax rate on income above a certain threshold.
+values:
+  2026-01-01: 0.02
+metadata:
+  unit: /1
+  period: year
+  label: Zohran Mamdani NYC high earner income tax rate
+  reference: 
+    - title: Mamdani Revenue Proposal
+      href: https://drive.google.com/file/d/14-aM9DKG337SDMilmfQtLRR-pDwyWSTc/view

policyengine_us/parameters/gov/local/ny/mamdani_income_tax/threshold.yaml

@@ -0,0 +1,10 @@
+description: Zohran Mamdani's proposed NYC income tax applies to income above this threshold.
+values:
+  2026-01-01: 1_000_000
+metadata:
+  unit: currency-USD
+  period: year
+  label: Zohran Mamdani NYC income tax threshold
+  reference: 
+    - title: Mamdani Revenue Proposal
+      href: https://drive.google.com/file/d/14-aM9DKG337SDMilmfQtLRR-pDwyWSTc/view

policyengine_us/reforms/local/ny/__init__.py

@@ -0,0 +1,4 @@
+from .mamdani_income_tax import (
+    create_nyc_mamdani_income_tax_reform,
+    nyc_mamdani_income_tax,
+)

policyengine_us/reforms/local/ny/mamdani_income_tax.py

@@ -0,0 +1,88 @@
+from policyengine_us.model_api import *
+from policyengine_core.periods import period as period_
+
+
+def create_nyc_mamdani_income_tax() -> Reform:
+    class nyc_mamdani_income_tax(Variable):
+        value_type = float
+        entity = Person
+        label = "Zohran Mamdani NYC income tax"
+        unit = USD
+        definition_period = YEAR
+        defined_for = "in_nyc"
+
+        def formula(person, period, parameters):
+            p = parameters(period).gov.local.ny.mamdani_income_tax
+            taxable_income = person("nyc_taxable_income", period)
+            threshold = p.threshold
+            rate = p.rate
+            # Apply 2% tax only to income above $1 million threshold
+            excess_income = max_(taxable_income - threshold, 0)
+            return excess_income * rate
+
+    class nyc_income_tax_before_credits(Variable):
+        value_type = float
+        entity = TaxUnit
+        label = "NYC income tax before credits"
+        unit = USD
+        definition_period = YEAR
+        defined_for = "in_nyc"
+
+        def formula(tax_unit, period, parameters):
+            taxable_income = tax_unit("nyc_taxable_income", period)
+            filing_status = tax_unit("filing_status", period)
+            filing_statuses = filing_status.possible_values
+            rates = parameters(period).gov.local.ny.nyc.tax.income.rates
+            regular_tax = select(
+                [
+                    filing_status == filing_statuses.SINGLE,
+                    filing_status == filing_statuses.JOINT,
+                    filing_status == filing_statuses.HEAD_OF_HOUSEHOLD,
+                    filing_status == filing_statuses.SURVIVING_SPOUSE,
+                    filing_status == filing_statuses.SEPARATE,
+                ],
+                [
+                    rates.single.calc(taxable_income),
+                    rates.joint.calc(taxable_income),
+                    rates.head_of_household.calc(taxable_income),
+                    rates.surviving_spouse.calc(taxable_income),
+                    rates.separate.calc(taxable_income),
+                ],
+            )
+            mamdani_tax = add(tax_unit, period, ["nyc_mamdani_income_tax"])
+            return regular_tax + mamdani_tax
+
+    class reform(Reform):
+        def apply(self):
+            self.update_variable(nyc_mamdani_income_tax)
+            self.update_variable(nyc_income_tax_before_credits)
+
+    return reform
+
+
+def create_nyc_mamdani_income_tax_reform(
+    parameters, period, bypass: bool = False
+):
+    if bypass:
+        return create_nyc_mamdani_income_tax()
+
+    p = parameters.gov.local.ny.mamdani_income_tax
+
+    reform_active = False
+    current_period = period_(period)
+
+    for i in range(5):
+        if p(current_period).in_effect:
+            reform_active = True
+            break
+        current_period = current_period.offset(1, "year")
+
+    if reform_active:
+        return create_nyc_mamdani_income_tax()
+    else:
+        return None
+
+
+nyc_mamdani_income_tax = create_nyc_mamdani_income_tax_reform(
+    None, None, bypass=True
+)

policyengine_us/reforms/reforms.py

@@ -95,6 +95,9 @@
 from .states.mi.surtax import (
     create_mi_surtax_reform,
 )
+from .local.ny.mamdani_income_tax import (
+    create_nyc_mamdani_income_tax_reform,
+)
 from .additional_tax_bracket import (
     create_additional_tax_bracket_reform,
 )
@@ -227,6 +230,9 @@ def create_structural_reforms_from_parameters(parameters, period):
         parameters, period
     )
     mi_surtax = create_mi_surtax_reform(parameters, period)
+    nyc_mamdani_income_tax = create_nyc_mamdani_income_tax_reform(
+        parameters, period
+    )
 
     american_worker_rebate_act = create_american_worker_rebate_act_reform(
         parameters, period
@@ -275,6 +281,7 @@ def create_structural_reforms_from_parameters(parameters, period):
         reconciled_ssn_for_llc_and_aoc,
         ctc_additional_bracket,
         mi_surtax,
+        nyc_mamdani_income_tax,
         additional_tax_bracket,
         american_worker_rebate_act,
     ]

policyengine_us/tests/policy/contrib/local/ny/nyc_mamdani_income_tax.yaml

@@ -0,0 +1,61 @@
+- name: Person below threshold in 2026
+  period: 2026
+  reforms: policyengine_us.reforms.local.ny.mamdani_income_tax.nyc_mamdani_income_tax
+  input:
+    gov.local.ny.mamdani_income_tax.in_effect: True
+    nyc_taxable_income: 800_000
+    state_code: NY
+  output:
+    nyc_mamdani_income_tax: 0
+
+- name: Person at threshold in 2026
+  period: 2026
+  reforms: policyengine_us.reforms.local.ny.mamdani_income_tax.nyc_mamdani_income_tax
+  input:
+    gov.local.ny.mamdani_income_tax.in_effect: True
+    nyc_taxable_income: 1_000_000
+    state_code: NY
+  output:
+    nyc_mamdani_income_tax: 0
+
+- name: Person above threshold in 2026
+  period: 2026
+  reforms: policyengine_us.reforms.local.ny.mamdani_income_tax.nyc_mamdani_income_tax
+  input:
+    gov.local.ny.mamdani_income_tax.in_effect: True
+    nyc_taxable_income: 1_200_000
+    state_code: NY
+  output:
+    # (1_200_000 - 1_000_000) * 0.02 = 200_000 * 0.02 = 4_000
+    nyc_mamdani_income_tax: 4_000
+
+- name: Person well above threshold in 2026
+  period: 2026
+  reforms: policyengine_us.reforms.local.ny.mamdani_income_tax.nyc_mamdani_income_tax
+  input:
+    gov.local.ny.mamdani_income_tax.in_effect: True
+    nyc_taxable_income: 2_000_000
+    state_code: NY
+  output:
+    # (2_000_000 - 1_000_000) * 0.02 = 1_000_000 * 0.02 = 20_000
+    nyc_mamdani_income_tax: 20_000
+
+- name: Pre-enactment test
+  period: 2025
+  reforms: policyengine_us.reforms.local.ny.mamdani_income_tax.nyc_mamdani_income_tax
+  input:
+    gov.local.ny.mamdani_income_tax.in_effect: False
+    nyc_taxable_income: 1_500_000
+    state_code: NY
+  output:
+    nyc_mamdani_income_tax: 0
+
+- name: Person not in NYC (no tax)
+  period: 2026
+  reforms: policyengine_us.reforms.local.ny.mamdani_income_tax.nyc_mamdani_income_tax
+  input:
+    gov.local.ny.mamdani_income_tax.in_effect: True
+    nyc_taxable_income: 1_500_000
+    state_code: CA
+  output:
+    nyc_mamdani_income_tax: 0