Open source tax software, by jurisdiction.
Tax software doesn't travel — a VAT library is only as useful as the jurisdiction it understands. Each page maps what the open-source ecosystem covers in one jurisdiction, and names what's still missing.
Engines, standards, and rules-as-code frameworks built to work across borders.
VAT validation, EN 16931 e-invoicing, and the plumbing of the single market.
ATO-adjacent datasets and community tooling for Australian tax.
The NF-e ecosystem — Brazil's mandatory e-invoicing, in four languages.
Crypto cost-basis and community calculators for Canadian rules.
Rules-as-code at national scale: OpenFisca, Catala, and open legal data.
The ELSTER ecosystem, payroll rules-as-code, and a German tax LLM.
GST compliance tooling for the world's largest indirect-tax overhaul.
FatturaPA and the SDI: structured e-invoicing libraries for Italy.
e-Tax automation and AI agents for Japanese filing.
Agent skills, vehicle tax, and income calculators for the Dutch system.
Aotearoa's tax and benefit system as executable rules.
Skatteetaten tooling and MCP access to Norwegian tax data.
KSeF: Poland's national e-invoicing system, with official open source.
VeriFactu, Facturae, and SII: Spain's anti-fraud invoicing stack.
Tunisia's tax-benefit system in OpenFisca.
e-Fatura and e-Arşiv clients for Turkey's GİB portals.
PolicyEngine, HMRC crypto rules, and capital gains done right.
IRS Direct File is open source. So is a whole filing ecosystem.