Every crypto tax tool we tried got our DeFi activity wrong — phantom gains on bridges, LP positions taxed as transfers, and no way to verify how a number was calculated. So we built ChainTax.
The most popular crypto tax tools were built in the US for IRS reporting. They default to FIFO cost basis, treat bridges as disposals, classify LP positions as transfers, and generate generic reports that don't map to SA108. When they added “UK support,” they bolted on Section 104 as an option and called it done.
Wrong cost basis method
FIFO is the default in most tools. HMRC requires Section 104 pooled average cost. Using the wrong method changes every gain calculation.
DeFi misclassification
Bridges taxed as disposals. LP deposits ignored. Staking rewards missing. Each error cascades through your Section 104 pools.
No audit trail
A report that says you owe £14,000 with no explanation of how it got there. Your accountant can't verify it. HMRC can't trace it.
Not a US tool with UK settings. A UK tax engine, built from scratch.
27 protocol-specific classifiers identify LP positions, bridges, staking, and swaps by decoding contract interactions — not guessing from token flows. Every classification has a confidence rating.
Every disposal shows exactly how the gain was calculated: which HMRC matching rule was applied (same-day, B&B, or Section 104), the pool snapshot before and after, the price source, and the confidence level. Nothing is a black box.
The 2024/25 tax year has two CGT rate regimes split at 30 October 2024. ChainTax automatically splits disposals at the boundary, computes Box 51, and fills SA108 boxes 13.1 through 13.8.
Built exclusively for HMRC from day one. Section 104 is the only cost basis method. Same-day and bed & breakfast rules are applied in the correct priority order. No FIFO defaults. No multi-jurisdiction compromises.
ChainTax Ltd is registered in Northern Ireland (NI739302). It was built by a UK crypto investor who needed accurate tax reports for their own DeFi activity across multiple chains and protocols — and couldn't find a tool that got it right.
The engine handles exchange trades and complex DeFi in one unified calculation. Every classification is deterministic. Every gain is traceable. The goal is simple: produce tax reports you can understand and your accountant can verify.
The numbers behind the engine.
1,699
Unit tests
Tax engine, classifiers, pricing, API routes
27
Protocol classifiers
Uniswap, Aave, Curve, Lido, and more
5
Chains
Ethereum, Polygon, Arbitrum, Optimism, Base
3
Exchange imports
Coinbase, Binance, Kraken
S104
Native pooling
The only cost basis method — as HMRC requires
Box 51
Split-year CGT
2024/25 rate change auto-computed
Independent security audit completed April 2026 — route-by-route code review covering auth, data access, payment flows, and concurrency.
Import your exchange trades or connect your DeFi wallets. See exactly how everything is classified. Pay only when you download the report.
75 transactions free · From £49 per tax year · No subscriptions ever