About Axiom
The Axiom Foundation publishes open, machine-readable encodings of the world's rules, starting with tax and benefit policy — statutes, regulations, and policy rules turned into cited, time-aware, executable code that anyone can run, audit, or reform.
Read the one-page overview →Why
The rules that decide who gets food assistance, health coverage, and tax credits are written in prose — then re-implemented, separately and privately, inside every eligibility system, calculator, and policy tool that needs them. The interpretation lives in closed code: hard to verify, harder to fix, duplicated everywhere. The Axiom Foundation publishes that layer in the open, so there is one cited, checkable source for what a rule actually computes.
What we build
The Axiom App
Explore the law: fetch and cite source documents, inspect the RuleSpec encodings that make them executable, and trace the logic through the computation graph. Every value cites its statute; every clause carries an effective date.
Explore →RuleSpec
The open format for encoding statutes and regulations as executable, cited rules.
Explore →The Encoder
An AI-assisted pipeline that reads a cited provision of source law, drafts its encoding, and leaves a signed manifest naming the source citation and the model for each encoding it applies.
Validation
The open-source harness that runs test cases through our encodings and another calculator or dataset, and publishes the results.
Explore →
How we verify
We compare encodings with other calculators and datasets and publish the results. In September 2026, our coverage map tied 14,030 of our 34,810 US rules to a program that a live comparison exercises, though a comparison of a program does not check each of its rules. The calculators include PolicyEngine, TAXSIM, UKMOD, EUROMOD, UNU-WIDER's SOUTHMOD, and Statistics Canada's SPSD/M. Max Ghenis is CEO of both Axiom and PolicyEngine, which he co-founded, and our TAXSIM runs use the TAXSIM executable that PolicyEngine packages. SOUTHMOD's licence bars giving its models to anyone else, so we run them by hand on our licensed machine, on synthetic households (the bundle has no Rwandan microdata at all), and none of the rules they check went through our encoder's apply step. We also replay USDA's SNAP quality-control cases from six states to check our benefit arithmetic; the file keeps only eligible households, so the replay leaves eligibility untested. Open isn't enough — the point is that you can check our work. Our team has spent years keeping tax-and-benefit rules correct at scale, in government, research, and open source.
See the validation dashboard →How we're organized
The Axiom Foundation is a fiscally sponsored project of the PSL Foundation, which also sponsors PolicyEngine. Our encodings and source corpus are public, and so is the code for the encoder, the rules engine and the comparison harness.
Browse the code on GitHub →Founding team
The Axiom Foundation's founding team is Max Ghenis (CEO and Founder), Ariel Kennan (President), and Pavel Makarchuk (Product Lead).
Meet the team →