United States
The United States has the deepest catalog here, anchored by the IRS's own Direct File release — the actual federal filing system, in the open. Around it: community filing engines, Form 1040 libraries, crypto cost-basis tools built for IRS rules, dynamic scoring models used in real policy analysis, and MCP servers that give agents access to tax data.
State coverage. Federal tooling is rich; most of the fifty state systems have no open implementation, which is exactly the gap Direct File's state integrations were meant to close.
18 projects tagged United States, ranked by community stars.
Privacy-focused, free, open-source cryptocurrency tax calculator for multiple countries: it handles multiple coins/exchanges and computes long/short-term capital gains, cost bases, in/out lot relationships/fractioning, and account balances. It supports FIFO, LIFO, HIFO and it outputs in form 8949 format. It has a programmable plugin architecture
USA Federal Individual Income and Payroll Tax Microsimulation Model
The PolicyEngine US Python package contains a rules engine of the US tax-benefit system, and microdata generation for microsimulation analysis.
The deterministic tax engine for AI agents. Highest score ever recorded on TaxCalcBench (96% exact returns)
An overlapping generations model framework for evaluating fiscal policies.
Python library to compute US federal taxes, and state taxes for some states.
Fully open-source US federal tax engine. Single binary cli. Runs on macOS, Linux, and Windows. Built for AI agents using AI agents.
TAXSIM emulator using the PolicyEngine US federal and state tax calculator
Runloop's AI TaxMan Project: an agent development starter that uses Codex & W&B Weave to process tax forms. Watch YouTube series: https://youtu.be/an7OMH_i8DU
TaxEase.AI is a user-friendly AI assistant designed to demystify and simplify US tax filing, a system that has become needlessly convoluted and stressful for millions of Americans.
MCP server for US individual taxpayers — 39 tools for federal/state tax calculations, credits, deductions, retirement strategies, and tax planning. All calculations run locally. TY2024 + TY2025 (OBBB Act).
Equity comp tax (ISO/NSO/RSU/QSBS), concentration, and hedging optimizer. MCP server + REST API with federal + 50-state + DC tax code, multi-year horizons.
MCP server for AI-assisted tax filing through FreeTaxUSA using Playwright browser automation
MCP server for AgentTax — tax compliance tools for AI agents