PolicyEngine New Zealand

PolicyEngine New Zealand is a microsimulation model for New Zealand’s tax and benefit system. It enables users to calculate the effects of taxes and benefits on households, and to simulate the impacts of policy reforms.

Features¶

• Comprehensive tax system modeling: Income tax, ACC levies, GST
• Working for Families: Family Tax Credit, In-Work Tax Credit, Best Start
• Social security benefits: Jobseeker Support, New Zealand Superannuation, Sole Parent Support, Supported Living Payment
• Additional support: Accommodation Supplement, Winter Energy Payment
• Retirement savings: KiwiSaver contributions and government support

Key Components¶

Tax System¶

• Personal income tax with progressive brackets (10.5%, 17.5%, 30%, 33%, 39%)
• ACC Earner’s Levy (1.67% on employment income up to cap)
• Goods and Services Tax (GST) at 15%

Benefits and Tax Credits¶

• Working for Families: Comprehensive family support system including Family Tax Credit, In-Work Tax Credit, and Best Start payments for young children
• Social Security: Jobseeker Support, New Zealand Superannuation (universal pension), and targeted support for sole parents and people with disabilities
• Housing Support: Accommodation Supplement to help with housing costs

Retirement Savings¶

• KiwiSaver: Auto-enrolment retirement savings scheme with employer and government contributions

Getting Started¶

pip install policyengine-nz

from policyengine_nz import NewZealandTaxBenefitSystem

# Create a tax and benefit system
system = NewZealandTaxBenefitSystem()

# Define a situation
situation = {
    "people": {
        "person": {
            "employment_income": {"2025": 50000},
            "age": {"2025": 30}
        }
    }
}

# Calculate income tax
from policyengine_core import Simulation
sim = Simulation(situation=situation, tax_benefit_system=system)
income_tax = sim.calculate("income_tax", "2025")
print(f"Income tax: ${income_tax[0]:,.2f}")

Official Data Sources¶

This model is built using official New Zealand government sources:

• Inland Revenue Department (IRD) - Tax rates, Working for Families, KiwiSaver
• Work and Income - Benefit rates and eligibility
• Ministry of Social Development - Social policy framework
• New Zealand Treasury - Economic modeling and analysis

Contributing¶

We welcome contributions! Please see our developer guide for information on how to contribute to PolicyEngine New Zealand.

License¶

PolicyEngine New Zealand is released under the AGPL-3.0 License.