Step 2 of 4 · ProjectsBy jurisdiction

All projects By jurisdiction United States

117 open source tax projects for United States.

Every project on the list for United States, grouped by kind. Global tools have a page of their own. Entries without a warning come first in each group; the labels mark what to check.

117 projects89 maintained52 on the map27 jurisdictions + globalFacts checked 6 Oct 2026

Browse these by tax area

Income tax Corporate tax Benefits Payroll tax VAT & indirect Cross-cutting

Tax engines

17 projects

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

accounting-harnessDeterministic accounting and audit harness with an ASC 740 module for the current and deferred provision.Tax engineUS

Cost-of-Capital-CalculatorCalculates the cost of capital and effective tax rates on new investment.Tax engineUS

IRS Fact GraphKnowledge-graph rules engine that models the US Internal Revenue Code, the calculation core of Direct File.Tax engineUS

IRS Form BuilderScala library that turns flow XML, fact dictionaries and locale files into questionnaire sites on Fact Graph.Tax engineUS

OG-CoreOverlapping-generations model framework for evaluating the economic effects of fiscal policy.Tax engineGlobal · US

OpenFileFree tax filing tool built on the published code of IRS Direct File.Tax engineUSFor individual taxpayersLicence unknown

OpenTaxUS federal tax engine as a single binary CLI built for AI agents; covers Form 1040 for 2025.Tax engineUSFor individual taxpayers

OpenTax EngineDeterministic US federal and state tax engine for AI agents with proof trees for each result.Tax engineUS

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

PolicyEngine TAXSIMTAXSIM emulator built on PolicyEngine's US federal and state tax calculator.Tax engineUS

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

section382Section 382 and 383 loss limitation engine: ownership-change analyser, annual limitation, anti-abuse rules.Tax engineUSLicence unknown

Tax-CalculatorFederal income and payroll tax microsimulation from the Policy Simulation Library.Tax engineUS

tax-logic-coreJavaScript library for US federal and state tax calculations, with IRS citations.Tax engineUSFor individual taxpayers

tenfortyPython package that computes US federal and state income tax and is built on Open Tax Solver.Tax engineUSFor individual taxpayers

UsTaxesFree web and desktop app to prepare US federal 1040 returns with data kept on the user's computer.Tax engineUSFor individual taxpayers

IRS Direct FileThe IRS filing tool. Shut down for 2026, but its code, Fact Graph included, is public.Tax engineUSArchivedDiscontinued · code public

Calculators

8 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

IRS Tax Withholding EstimatorThe IRS Tax Withholding Estimator, built on Fact Graph and Form Builder.CalculatorUS

py1040Python program that computes US federal Form 1040 income tax from an interview and an input form.CalculatorUSFor individual taxpayers

RP2Privacy-focused crypto tax calculator with country plugins and FIFO LIFO and HIFO accounting.CalculatorUS · JP · ES · IEFor individual taxpayers

tax-extension-payment-calculatorClient-side calculator for 2025 US federal and California extension payments, with penalties and interest.CalculatorUSFor individual taxpayersLicence unknown

tax-helper (hinosxz)Next.js app for French and US citizens filing taxes on income from company equity (RSUs, ISOs, ESPP).CalculatorFR · USFor individual taxpayersLicence unknown

asc740-tax-provisionSix-sheet linked Excel model of a corporate income tax provision under ASC 740 for a hypothetical company.CalculatorUSDemoLicence unknown

tax-toolPython script that works out cost basis for VMware shares after the Broadcom merger from E*TRADE exports.CalculatorUSInactive since 2025For individual taxpayersNon-commercial use only

Agent skills

1 project

Packaged tax expertise an AI agent can follow, step by cited step.

ASC-740-SKILLAgent skill for a 12-phase ASC 740 provision: current and deferred schedules, valuation allowance, UTPs, ETR.Agent skillUSLicence unknown

MCP

9 projects

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

irs-taxpayer-mcpMCP server with 44 local tools for US federal and state tax estimates, credits and planning.MCPUSFor individual taxpayers

mcp-htsMCP server for US tariff rates from the USITC schedule, through a free gateway or a local stdio server.MCPUS

optionsahoy-mcpMCP server that models the federal and state tax on equity pay: ISOs and AMT, NSOs and RSUs.MCPUSFor individual taxpayers

tariff-everywhereLocal US HTS lookup in SQLite with a CLI and an MCP server.MCPUSHippocratic License 3.0

tariff-resolverMCP server for US import duty research from bundled USITC data: Chapter 99, MPF and HMF fees, landed cost.MCPUS

agenttax-mcpMCP server that tracks US sales-tax obligations for paid MCP tools and AI agents.MCPUSNeeds a paid service

BoomTax MCP serverMCP server to query BoomTax filings, forms and e-file status for US information returns.MCPUSNeeds a paid serviceLicence unknown

FreeTaxUSA MCP ServerMCP server that drives FreeTaxUSA in a browser; navigation and personal-info tools work, the rest are stubs.MCPUSNeeds a paid serviceFor individual taxpayers

LR Labs MCP connectorMCP client for a hosted engine that screens Indian transfer pricing safe harbour, thresholds and range.MCPIN · USNeeds a paid service

APIs

6 projects

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

Corporation-Accounting-SkillFastAPI service for an accountant agent: ASC 740 provision checklists, book-to-tax differences, journals.APIUSLicence unknown

hs-code-lookupJavaScript library that parses, validates and looks up HS codes with MFN duty rates for US, EU, UK and China.APIUS · EU · UK · CN

QWED-TaxDeterministic check, built on the Z3 solver, that verifies AI-generated tax decisions before they run.APIUS · IN

Taxsim.jlJulia interface to TAXSIM, the NBER's calculator for US federal and state income taxes.APIUS

AvaTax REST v2 PHP SDKPHP SDK for the AvaTax REST v2 API, a hosted tax calculation service.APIUSNeeds a paid service

tax-treaties (LuckStock)Node microservice serving US tax treaty articles and royalty withholding rates, with country reference data.APIUSInactive since 2017

Automations

37 projects

Reusable workflows for provisions, reconciliations and compliance runs.

amazon-state-sales-and-tax-summaryTurns marketplace order exports into state-by-state sales and tax totals for US sales-tax returns.AutomationUS

caseflowTariff classification with legal reasoning for Nigeria's ECOWAS common external tariff and the US HTS.AutomationNG · USLicence unknown

CFO StackBeancount accounting run through Claude Code, with jurisdiction packs for Canada, the US, Taiwan and China.AutomationCA · US · TW · CNFor individual taxpayers

DaLI for RP2Data loader that turns exchange and wallet records into input files for the RP2 crypto tax calculator.AutomationUS · JPFor individual taxpayers

fatca-ides-phpPHP library that converts bank client data into FATCA XML packages for the IRS IDES gateway.AutomationUS · Global

hs-code-lookup (AccioWork)HTML tool to find 6-digit HS and 10-digit HTS codes for 15 or more product categories, with 2026 rates.AutomationUS

hscode-worksheet-extensionChrome extension that generates US HTS codes and customs worksheets offline for eBay exporters; Japanese.AutomationUS · JPFor individual taxpayersLicence unknown

japan-expat-tax-checkerTax filing checklist for US expats in Japan: FBAR, FATCA, RSU and NISA/iDeCo.AutomationUS · JPFor individual taxpayers

OCA l10n-usa (Odoo)Odoo US localisation with a hybrid sales tax engine (local rates first, API fallback), ACH and 1099 modules.AutomationUS

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

Taxentia AIAI tax research assistant for tax professionals, with cited analysis.AutomationUS

taxguard-xaiResearch framework that ranks IRS Form 990 filings for human review, with explainable signals.AutomationUS

ai_tax_agentLangChain agent that scores and simplifies the US tax code, using the IRC, IRS bulletins and SOI data.AutomationUSInactive since 2025

AI-tax-agent (janimiyarj)Flask app that prepares a basic US federal return as a PDF and answers questions with OpenAI.AutomationUSInactive since 2025DemoNeeds a paid serviceFor individual taxpayers

AI-Tax-Agent (Raj-Shah-20)Flask prototype that computes US federal tax on 2025 brackets and generates a simplified Form 1040.AutomationUSInactive since 2025DemoFor individual taxpayers

AI-Tax-Return-AgentReads W-2, 1099-NEC and 1099-INT files, computes 2024 US tax and fills a Form 1040.AutomationUSInactive since 2025DemoFor individual taxpayersLicence unknown

codex-tax-manStarter that turns a mock tax-prep website into an AI agent service on Runloop, from W-2s to Form 1040.AutomationUSDemoNeeds a paid serviceFor individual taxpayers

ComparableBotUiPath robot and VBA saving US comparables' 10-K filings from the SEC and building a TNMM adjustment workbook.AutomationUSInactive since 2021DemoNeeds a paid service

fatca-data-preparationJava FATCA data package preparation with sample IDES payloads.AutomationUS · GlobalInactive since 2023Licence unknown

FATCAXMLBatcherJava utility that builds, parses and batches FATCA XML files.AutomationUS · GlobalInactive since 2016Licence unknown

harmonized_tariffRuby utility that converts the US Harmonized Tariff Schedule from hts.usitc.gov into JSON, SQL and XML.AutomationUSInactive since 2025

HS-Code-Lookup-for-CustomsHS lookup traced to 177,000 CBP CROSS rulings behind a confidence gate; classifying needs model API keys.AutomationUSDemoNeeds a paid service

HTS-ClassifierLangGraph and Claude HTS classifier with a web demo; needs OpenAI, Pinecone and Anthropic keys.AutomationUSDemoNeeds a paid service

IRS IDES data preparation samplesIRS sample code (.NET, Java, OpenSSL, shell) for encrypting and packaging FATCA submissions for IDES.AutomationUSArchived

irs-agentScreenpipe-based agent that logs receipts, invoices and tax documents seen on screen into a local database.AutomationUSInactive since 2025DemoFor individual taxpayers

java-email-parserJava tool that fetches and parses FATCA IDES notification e-mails.AutomationUS · GlobalInactive since 2016Licence unknown

Open-Source-Tax-ToolingResearch on open source bookkeeping tools as inputs for US consumer tax software, with a hledger prototype.AutomationUSDemoFor individual taxpayers

Recommender-System-for-BenchmarkingScript ranking S&P 500 companies by similarity of margin, markup and sector as transfer pricing comparables.AutomationUSInactive since 2020DemoLicence unknown

tax-filing-agentReact and Express app for US federal return preparation with an AI chat assistant and 2025 brackets.AutomationUSDemoFor individual taxpayers

tax-fraud-xaiBoosted-tree and neural model with SHAP explanations that flags fraudulent filings, on synthetic data.AutomationUSInactive since 2025Demo

tax-prep-agentCommand-line assistant on the Claude Agent SDK that classifies tax documents and reviews returns.AutomationUSDemoNeeds a paid serviceFor individual taxpayersLicence unknown

Tax-Provision-AgentAI tax provision agent on AWS Bedrock with 19 tools, among them GILTI, FTC, BEAT, Pillar Two and 25 US states.AutomationUSNeeds a paid service

TaxEase.AIVertex AI assistant that guides US filers to the right IRS forms and answers questions from IRS documents.AutomationUSInactive since 2024DemoNeeds a paid serviceFor individual taxpayers

transfer-pricing-arms-length-analysisWeb app and CLI: Claude extracts tested-party facts, EDGAR comparables are screened, a TNMM range goes to PDF.AutomationUSDemoNeeds a paid serviceLicence unknown

transfer-pricing-benchmarking-toolTNMM benchmarking pipeline on Yahoo Finance data: screening, profit level indicators and interquartile range.AutomationUSDemo

TurboTPLangGraph and Gemini workspace for transfer pricing research, Local and Master File drafts, a RAG assistant.AutomationUS · GlobalDemoNeeds a paid serviceCC BY-NC 4.0

us-hts-classifierLLM agent that classifies to the HTSUS, grounded in schedule notes and CBP CROSS precedent; a prototype.AutomationUSDemo

Tax datasets

31 projects

Rates, treaties and statistics, open and versioned.

apparel-hs-codesOpen JSON database of apparel and textile HS codes with MFN duty rates for the US, EU, UK and Australia.Tax datasetUS · EU · UK · AU

code_tcja_profit_shiftingNotebooks and data for Garcia-Bernardo, Janský and Zucman on whether the TCJA cut profit shifting by US MNEs.Tax datasetUSLicence unknown

CPS Tax Filing UnitsUS Congressional Budget Office code that builds tax-filing units from Current Population Survey data.Tax datasetUS

cross_rulings_hts_dataset_for_tariffs18,731 US CBP CROSS rulings paired with HTS codes for tariff classification models (the ATLAS paper).Tax datasetUS

DeepCalc tax rate dataOpen tax rate data as JSON and an npm package: US federal income tax, EU VAT, US sales tax for 10 states.Tax datasetUS · EU

GAAP-Implementation-ToolkitTracks how US public companies implement standards, ASC 740 among them, from SEC EDGAR data.Tax datasetUS

htsdataUS HTS data as JSON, served through jsDelivr.Tax datasetUSLicence unknown

myTransferPricing referenceSummaries of 18 OECD transfer pricing country profiles, with a prompt that reviews a Local File against one.Tax datasetAT · BE · BR · DK · FR · DE · GR · IE · IT · LU · NL · PL · SG · ES · SE · CH · UK · US

originshiftUS non-preferential rules of origin (19 CFR 102.20 and 102.21) as a machine-readable corpus with a CLI.Tax datasetUS

PSL taxdataPrepares microdata for US tax microsimulation with Tax-Calculator.Tax datasetUS

State Estate Tax DatasetUS state estate and inheritance tax exemptions and rates, as an open dataset.Tax datasetUS

taric-opendataAutomated mirrors of tariff data from 18 sources (EU TARIC, GB, NO, CH, US) plus EBTI and ATaR rulings.Tax datasetEU · UK · NO · CH · US · Global

tax-microdata-benchmarkingDevelops a benchmarked general-purpose dataset for US tax reform analysis.Tax datasetUSLicence unknown

US Tax DatasetUS sales-tax rates, nexus thresholds and SaaS taxability, with a source for every record.Tax datasetUSPolyForm Internal Use 1.0.0

us-dividend-whtCC0 dataset of US dividend withholding rates for non-residents by country of residence, CSV and JSON.Tax datasetUS · Global

us-import-duty-hs6US duty rates by HS6 for consumer goods, including Section 301 and effective rates for Chinese origin.Tax datasetUS

us-sales-tax-20262026 US state sales-tax and lodging-tax rates for all 50 states, as an MIT-licensed dataset.Tax datasetUS

us-tariff-dataUS HTS as CSV and JSON with Chapter 99 duties by country, and EU duties by origin; a vendor's data dump.Tax datasetUS · EU

CBCR (Dan-Kolar)Jupyter notebook and CSV of IRS country-by-country statistics; seminar material for a public economics course.Tax datasetUSInactive since 2022DemoLicence unknown

chapter_99_traversalTraversable CSV representation of HTS Chapter 99 from the USITC API.Tax datasetUSInactive since 2025Licence unknown

Harmonized Tariff Schedule of the United States 2025The 2025 US HTS as a clean dataset with text-model baselines predicting tariff outcomes; educational.Tax datasetUSInactive since 2025Demo

MNCs and Tax Havens: CbCR (Garcia-Bernardo, Janský, Tørsløv)Jupyter notebooks and data behind a 2021 paper on effective tax rates and profit shifting to tax havens.Tax datasetUS · GlobalInactive since 2021

Offshore Profit Shifting and Aggregate Measurement (data and code)Data and code for Guvenen et al. on how US MNEs' profit shifting distorts US macro statistics, 1983-2016.Tax datasetUSInactive since 2022Licence unknown

Offshore_Profit_Shifting_Replication.jlJulia port of the Guvenen et al. (AER 2022) replication package on US offshore profit shifting measurement.Tax datasetUSInactive since 2023

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

replication_cbcr (formulary apportionment)Jupyter notebook allocating US MNEs' IRS CbCR profits under formulary apportionment variants (GFA, IMF, OECD).Tax datasetUS · GlobalInactive since 2019Licence unknown

Synthetic Tax Dataset GeneratorPython scripts that generate synthetic US tax forms such as W-2, 1099 and 1040 as PDF documents.Tax datasetUSDemoFor individual taxpayersLicence unknown

tariffs-profit-shiftingPython code and data for a capstone paper on whether Section 301 tariffs made US firms shift profits abroad.Tax datasetUSDemoLicence unknown

TaxDatasetGeneratorPython generator of synthetic US federal tax return data for testing and training.Tax datasetUSDemoFor individual taxpayersLicence unknown

Taxing across Borders (Zucman) dataJEP 2014 replication data for Zucman's 'Taxing across Borders': one Excel workbook and a short ReadMe.Tax datasetUS · GlobalInactive since 2019Licence unknown

Territorial Tax Reform and Profit Shifting (Hasegawa) replicationStata do-files for Hasegawa's paper on territorial tax reform and profit shifting by US and Japanese MNEs.Tax datasetUS · JPInactive since 2024

Legal datasets

2 projects

Statute, case law and guidance your agents can cite.

CourtListenerFree Law Project archive of opinions and dockets, with a public API.Legal datasetUS

US Tax Law QASynthetic dataset of 4,000 US federal tax law questions with IRAC reasoning and IRC citations.Legal datasetUSDemo

Benchmarks

5 projects

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

harvey-labs (Legal Agent Benchmark)Legal Agent Benchmark: 2,010 legal tasks with documents and rubrics and a Python harness; 34 tasks are tax.BenchmarkUS

LLM-Tax-AbuseCode and US tax-strategy data from the paper on whether LLMs can identify and generate tax abuse.BenchmarkUSLicence unknown

SARAStatutory reasoning benchmark built on the US Internal Revenue Code.BenchmarkUS

TaxCalcBenchBenchmark that tests frontier AI models on US tax return calculations.BenchmarkUS

TaxBench114 expert-written US tax questions with grading rubrics for testing LLMs; 19 touch transfer pricing or s.482.BenchmarkUSInactive since 2025

Models

1 project

Open AI models trained or tuned for tax text.

tax-position-risk-prototypeResearch prototype classifying uncertain tax positions with knowledge-guided features on synthetic data.ModelUSDemoLicence unknown

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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.