My own DeFi history still needed too much manual checking across fragmented exports and multi-step transactions. ChainTax was built to classify the activity it understands and show where evidence or judgement is still required.
Code review completed April 2026, covering auth, payments and concurrency. Read the scope.
Tax engine, classifiers, pricing, API routes.
Same-day, 30-day B&B, S104 pooling. Split-year CGT auto-computed for 2024/25.
Pay per tax year. 14-day refund before download. Secure payment via Stripe.
Gold-level Innovator awarded by InnovateNI, April 2026.
UK crypto tax becomes difficult when exchange exports, wallets and DeFi activity are incomplete or interpreted separately. A defensible result needs the full history, the correct UK matching order, and enough detail for the user or accountant to inspect the calculation.
Fragmented history
An omitted exchange, wallet or acquisition can change the shared Section 104 pool and every later disposal that uses it.
Multi-step DeFi
Bridges, LP positions, wrappers and staking can involve several linked legs. Unsupported or ambiguous activity needs visible review.
Thin evidence
A total without the matching rule, source value and pool movement is harder for a user or accountant to challenge and verify.
Not a US tool with UK settings. A UK tax engine, built from scratch.
34 protocol-specific classifiers cover supported LP positions, bridges, staking, and swaps by decoding contract interactions. Unresolved activity stays visible for review.
Every disposal shows how the stored figure 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.
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. Section 104 is the only cost-basis method, with same-day and bed-and-breakfast rules applied before the pool in the required order.
ChainTax Ltdis registered in Northern Ireland (NI739302) and holds a Gold-level Innovator award from InnovateNI (April 2026). I'm a UK crypto investor. I built ChainTax because I needed accurate tax reports for my 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 result 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, updated daily on the live stats page.
4,800+
Unit tests
Tax engine, detectors, pricing, API routes
34
Protocol detectors
Uniswap, Aave, Curve, Lido, Yearn, Convex, EigenLayer, Blur, Seaport NFTs, airdrops, and more
5
Chains
Ethereum, Polygon, Arbitrum, Optimism, Base
4
Native CSV parsers
Coinbase, Binance and Kraken; Crypto.com App (beta)
S104
Native pooling
The matching method HMRC requires
Box 51
Split-year CGT
The 2024/25 split-year rate change, auto-computed. 2025/26 and 2026/27 run a flat 18% / 24%.
Independent security audit completed April 2026, a route-by-route code review covering auth, data access, payment flows, and concurrency.
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