Open-source crypto tax skills for Claude, ChatGPT, and any LLM. Rules as code (well — rules as markdown). Verified against primary IRS / HMRC / BZSt sources. Free. AGPL-3.0.
Upload the skill for your jurisdiction to your LLM's project knowledge, then ask your crypto tax questions. No sign-up, no account, no telemetry.
Companion to dTax — the AGPL-licensed crypto tax engine. These skills handle education and small-scale reasoning. When you hit their ceiling (large transaction sets, DeFi position unwinding, 8949 generation, multi-year basis tracking), dTax is the production tool.
skills/
├── us/ ← Federal + state-level rules
├── uk/ ← HMRC Section 104 pooling, CARF
├── de/ ← §23 EStG one-year rule
└── ... ← contributions welcome
- Claude.ai → Create a Project → Add files as Project Knowledge
- ChatGPT → Attach files to conversation or create a Custom GPT
- Anywhere else → Paste or attach the
.md
I sold 0.5 BTC in 2025 that I bought across three wallets in 2023.
How does Rev. Proc. 2024-28 affect my cost basis?
The skill tells the LLM how to reason about the rule, not just what the rule is.
Each skill .md contains:
| Section | Purpose |
|---|---|
| Authority | Primary source (IRS Rev. Proc., HMRC manual, court case) with effective date |
| Plain-language summary | What the rule actually does |
| Decision tree | How to classify a specific transaction under this rule |
| Worked examples | 3-5 realistic crypto scenarios with numbers |
| Edge cases | The stuff that trips up AI models and accountants alike |
| Version / last verified | Quality tier + date of last primary-source check |
| When to use dTax | The ceiling of this skill + production-path handoff |
Every skill declares its quality tier in the frontmatter:
| Tier | Meaning |
|---|---|
| Q1 | Battle-tested — verified against primary authority + cross-checked against dTax engine computation |
| Q2 | Research-verified — primary source read, examples sanity-checked, not yet production-tested |
| Q3 | Draft / community contribution — use with care, verify before relying on |
We publish the tier because most "150-country support" claims in crypto tax are vaporware. If a skill is Q3, we say so.
Crypto tax rules are public knowledge (IRS Rev. Proc., HMRC manuals, court cases). Hiding our interpretation behind a paywall would be rent-seeking on top of public information. We publish because:
- Education should be free. Understanding Rev. Proc. 2024-28 shouldn't require a $299 subscription.
- Verifiable > trust me. AGPL + public skills = anyone can audit our interpretation.
- Companion, not replacement. These skills can't import 10,000 transactions, can't cluster on-chain addresses, can't generate IRS Form 8949. dTax does. The skills teach the rule; dTax runs the computation.
See CONTRIBUTING.md. Core requirements:
- Cite primary authority. No blog-post hearsay.
- Include at least one worked example with actual numbers.
- Declare edge cases honestly. If a rule is ambiguous, say so.
- Tag the Q-tier. Don't overclaim.
AGPL-3.0 — same as dtax core. If you use these skills in a commercial product, your product must also be AGPL-compliant or obtain a commercial license from dTax Inc.
Individual users preparing their own returns, accountants assisting clients, educators, and AGPL-compatible open-source projects need no special license.
These skills implement our best-faith reading of tax authority. They are not a substitute for a qualified tax professional. Tax law changes; check the last_verified date in each skill and consult your CPA for filing decisions.
- dTax — production crypto tax engine (AGPL-3.0 core)
- dtax monorepo — the engine these skills were distilled from
- Open Accountants — general-purpose tax skills by Glimpse Ltd. Different scope (all-sector, 134 countries, CPA review loop) — same distribution instinct.