Terms, in plain words.

Last updated 26 August 2026. Operated from the United Kingdom, full company details will appear here when gains.tax's registration completes.

What gains.tax is

A calculator that runs on your device. It applies published UK tax rules to data you give it and shows its working, including the HMRC manual paragraphs it relied on. It is information, not tax advice, and it does not know your wider circumstances. You are responsible for what you file. If your affairs are complicated, involve a professional.

Your data, your machine, your backups

Because your data never reaches us, we cannot recover it for you. Use the app's session export and keep your own backups. We are not liable for data lost from your own device or browser storage.

The free tier and the account fee

Under 1,000 transactions the app is free, including report downloads. The account fee covers 1,000 to 9,999 transactions and all tax years, past and future, for the person who bought it. It is a one-time payment, not a subscription. Keys are for your own use on your own devices. Trader and Desk keys work the same way at their own transaction limits.

Refunds and cancellation

Fourteen days from purchase, full refund, one email to [email protected]. No form and no reason required, and you keep any reports you already downloaded. We ask only that you stop using the key, which stops working on the tier it opened once the refund is issued. There is nothing to cancel beyond that, because there is no subscription and no recurring charge, so no renewal will ever appear on your statement.

This sits alongside your statutory rights, it does not replace them. If a refund is due to you under consumer law after those fourteen days, the law wins.

Accuracy

We work to keep the engine correct against published HMRC guidance and cite what it does. Software has bugs, source data has gaps, and the output is only as good as the data you import. Check your reports before filing, the app is built to make checking easy.

We do not ask you to take that on faith. Every tax rule the engine applies is published at /verification/ with the statute it comes from and the HMRC worked example it is tested against, and that page is generated only when the engine's test suite passes. If you find an error in the engine, email [email protected]. On a confirmed error we fix it and republish promptly, and the corrected engine reaches every user, paid and free, at no charge.

Acceptable use

Do not use the app or the relay to break the law, to abuse exchanges' APIs, or to attempt to disrupt the service. The professional directory's contact details are for engaging professionals, not for scraping or marketing.

The legal lines

The service is provided as is, and to the extent the law allows, liability is limited to the amount you paid us, which for most users is nothing. These terms are governed by the law of England and Wales. Nothing in them limits liability that cannot lawfully be limited.

That cap is the ordinary legal floor, not the standard we hold ourselves to. The standard is the one above: rules published with their statutes and HMRC's own worked examples at /verification/, a confirmed engine error fixed and republished promptly, and a real person at [email protected] to report one to.