The crypto tax tool that shows its working.
Run the same trades through different crypto-tax tools and you often get different numbers — with no way to see which is right. For a tax return you sign, that isn't good enough. CryptoCGT was built to fix exactly that: it implements HMRC's own rules, reproduces HMRC's published worked examples to the penny, and lets you check the working behind every figure.
How the numbers are worked out
The maths isn't our opinion — it's HMRC's law, implemented directly and checked against independent sources. Here is exactly how, so you never have to trust a black box.
Built on HMRC's rules, to the letter
Capital Gains is computed with Section 104 pooling and the same-day and 30-day “bed & breakfast” matching rules, exactly as set out in HMRC's Cryptoassets Manual. The annual exempt amount and the correct rates for each tax year are applied automatically.
Checked two independent ways
The engine reproduces every one of HMRC's own worked examples to the penny, and is cross-checked against BittyTax, an independent open-source UK CGT calculator. When two separate implementations of the same law agree to the penny, you can trust the figure.
Every figure shows its working
Click any number and you see exactly which trades and which matching rule produced it — proceeds, cost, and gain, line by line. Nothing is hidden, so you (or your accountant) can check it before you file.
Never confidently wrong
If your data is incomplete or a price can't be confirmed, CryptoCGT says so and marks the figure provisional— and won't let you download a report it can't stand behind. A tax tool should never hand you a confident number it isn't sure of.
Why I built CryptoCGT
I'm Mai Thanh Tung — a software engineer trained at FPT University, one of Vietnam's leading technology universities, and I've spent the last eight years in crypto. In all that time, the same thing happened every tax season: the tools each gave a different number, and none of them showed their working — so you were asked to sign a return on a figure you couldn't check. I'd felt that frustration first-hand. So I built CryptoCGT to fix the one thing that matters: implement HMRC's own rules to the letter, reproduce HMRC's published worked examples to the penny, and show the working behind every figure — so you can actually trust the number before you file it.
Your data, and your funds
We never touch your funds
CryptoCGT works from a CSV export or manual entry only. We never ask for exchange API keys, never connect to your accounts, and have no way to move or withdraw your crypto. Read-only by design.
Independent by design
CryptoCGT isn't owned by or affiliated with any exchange, so the numbers aren't shaded to sell you anything. Payments are handled by Paddle as Merchant of Record. Our full business and operator details are on the Contact page, and you can reach us anytime at [email protected].
CryptoCGT is an information tool, not a regulated tax adviser. It helps you compute and understand your UK Capital Gains Tax under HMRC's published rules, but it is not a substitute for advice on your specific circumstances from a qualified accountant.
See your real number — free.
Drop in a CSV and watch every figure explain itself. You only pay to download.