Step 2 of 4 · ProjectsBy tax area

39 open source projects for benefits.

Every project on the list whose tax area includes Benefits, grouped by kind. Entries without a warning come first in each group; the labels mark what to check.

39 projects35 maintained34 on the map19 jurisdictions + globalFacts checked 6 Oct 2026

Browse these by jurisdiction

Global United Kingdom United States Canada France Japan Paraguay Argentina Australia Austria Czechia European Union Germany India Netherlands New Caledonia New Zealand Senegal South Korea Tunisia

Tax engines

24 projects

Rules-as-code that compute liabilities, returns and reforms.

EUROMODThe EU tax-benefit microsimulation model, maintained by the Joint Research Centre.Tax engineEU

GETTSIMThe German Taxes and Transfers Simulator: a microsimulation model of German taxes and benefits.Tax engineDE

OpenFiscaRules-as-code framework: legislation written in Python, served as a web API.Tax engineFR · Global

OpenFisca ArgentinaEarly OpenFisca model of Argentina's tax and benefit system.Tax engineAR

OpenFisca AustriaEarly OpenFisca model of Austria's tax and benefit system.Tax engineAT

OpenFisca CzechiaEarly OpenFisca model of the Czech tax and benefit system.Tax engineCZ

OpenFisca FranceThe French tax and benefit system, written as OpenFisca rules.Tax engineFR

OpenFisca IndiaEarly OpenFisca model of India's tax and benefit system.Tax engineIN

OpenFisca JapanJapan's tax and benefit rules as an OpenFisca API, with a web app on top.Tax engineJP

OpenFisca KoreaEarly OpenFisca model of South Korea's tax and benefit rules.Tax engineKR

OpenFisca NLEarly OpenFisca model of Dutch tax and benefit rules.Tax engineNL

OpenFisca Nouvelle-CalédonieNew Caledonia's tax and benefit system for OpenFisca.Tax engineNC

OpenFisca ParaguayParaguay's tax and benefit system for OpenFisca.Tax enginePY

OpenFisca SenegalSenegal's tax and benefit system for OpenFisca.Tax engineSN

OpenFisca TunisiaTunisia's tax and benefit system for OpenFisca.Tax engineTNLicence unknown

PolicyEngineOpen tax-benefit models with a public app for scoring policy reforms.Tax engineUS · UK

PolicyEngine AustraliaMicrosimulation model of Australia's tax and benefit system.Tax engineAULicence unknown

PolicyEngine CanadaModel of Canada's tax and benefit system, built on PolicyEngine Core.Tax engineCA

PolicyEngine CoreCore microsimulation engine for PolicyEngine models, forked from OpenFisca Core.Tax engineGlobal

PolicyEngine UKOpen-source static tax-benefit microsimulation model for the UK.Tax engineUK

PolicyEngine USRules engine and microsimulation model of the US tax-benefit system.Tax engineUS

policyengine.pyPolicyEngine's Python package that brings the country models, analysis and charts together.Tax engineGlobal

OpenFisca AotearoaNew Zealand's legislation, regulation and policy as OpenFisca rules-as-code.Tax engineNZInactive since 2025

OpenFisca Canada (DTS)Experiment using OpenFisca as a rules engine for Canadian legislation, a jumping-off point for further work.Tax engineCAInactive since 2021Licence unknown

Calculators

2 projects

Small tools that compute one tax for one country.

IRS EITC AssistantThe IRS Earned Income Tax Credit Assistant questionnaire, built on Fact Graph and Form Builder.CalculatorUS

retirement_income_tax_planner_CanadaBrowser planner for Canadian retirement income: RRIF, TFSA, CPP, OAS, tax and investment scenarios.CalculatorCAFor individual taxpayersPolyForm Noncommercial 1.0.0

MCP

3 projects

Open connectors and protocols between agents and legislation, case law and ledgers.

OpenFisca Japan MCPMCP server with tools for OpenFisca Japan, the Japanese tax and benefit model.MCPJP

OpenFisca MCPMCP interface for interacting with OpenFisca calculations.MCPGlobalLicence unknown

PolicyEngine MCPMCP server for PolicyEngine's database and tax-benefit simulations.MCPGlobalInactive since 2025Licence unknown

APIs

1 project

Validation, rates, filings and registries you can call directly.

PolicyEngine APIREST API that computes the impact of tax and benefit policies with the PolicyEngine models.APIGlobal

Automations

2 projects

Reusable workflows for provisions, reconciliations and compliance runs.

PolicyEngine ChatChat interface to PolicyEngine for UK and US tax and benefit questions and reforms.AutomationUS · UKLicence unknown

PolicyEngine UK ChatChat assistant for UK tax and benefit policy, powered by PolicyEngine.AutomationUKLicence unknown

Tax datasets

6 projects

Rates, treaties and statistics, open and versioned.

OpenFisca France dataSurvey and administrative data inputs for OpenFisca France microsimulation.Tax datasetFR

OpenFisca Paraguay dataData for the OpenFisca Paraguay model.Tax datasetPYLicence unknown

OpenFisca policyHelpers for policy analysis on survey data with OpenFisca.Tax datasetGlobal

OpenFisca survey managerTool for managing the survey data used in OpenFisca microsimulations.Tax datasetGlobal

PolicyEngine UK dataBuilds calibrated UK household microdata for PolicyEngine, reweighted against national targets.Tax datasetUKLicence unknown

PolicyEngine US dataBuilds representative US household microdata for PolicyEngine from survey data, calibrated to admin targets.Tax datasetUSArchivedLicence unknown

Benchmarks

1 project

Evals that show whether a model reasons about tax, or guesses.

PolicyBenchBenchmark of how well frontier AI models estimate household tax and benefit outcomes without tools.BenchmarkGlobal

Labels mark what to check before you rely on an entry: inactive or archived code, demos, paid services and unclear licences. Only maintained projects for companies and tax authorities appear on the map. Search and filter the whole list.

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Next · Step 3 of 4The gapsThe activities with no open project yet, and the partly covered ones, with what to build on.