In this guide
If HMRC writes to say it's checking your tax, don't panic. This is a compliance check, sometimes called a tax enquiry. HMRC will write or call to tell you what it wants to check and why.
First steps
- Read exactly what's being checked: which tax, which tax year or period, and what information HMRC wants.
- Note the reply date and reply on time. If you don't understand something, or need more time, contact the officer named in the letter. You can ask for more time if you have a good reason.
- Keep filing and paying as normal: your other returns and payments are still due during the check.
- If you're unsure a letter or call is really from HMRC, check using the official contact details on GOV.UK.
Your rights
- Get help: you can formally authorise a tax agent, or give temporary authorisation.
- Ask for a review: if you disagree with a decision, you can ask for a review by a different officer within 30 days.
- Appeal: you can appeal to an independent tax tribunal.
- Mediation: you can apply for alternative dispute resolution.
How far back HMRC can go
| Situation | Time limit |
|---|---|
| Normal (you took reasonable care) | 4 years |
| Careless | 6 years |
| Offshore income or assets involved (not deliberate) | 12 years |
| Deliberate | 20 years |
Time limits run from the end of the tax year concerned. If you never registered when you should have, it can also go back up to 20 years.
About the 12 years: it applies to Income Tax and Capital Gains Tax (for 2015 to 2016 onwards) and to Inheritance Tax. It doesn't apply if HMRC already received enough information through international exchange, such as the Common Reporting Standard (CRS) under which tax authorities share bank account information, to have dealt with it within the normal time limits. In other words, HMRC can get information about overseas accounts through these channels.
Readers ask: during a check, can I hand over only some of my bank records?
No. Give complete and accurate information. Deliberately hiding income counts as deliberate behaviour, which means HMRC can go back up to 20 years and penalties are higher.
Found a mistake in the past? Tell HMRC first
- Voluntary disclosure: penalties are usually lower. Telling HMRC before it contacts you (unprompted) gets a bigger reduction than telling it after (prompted).
- How: usually through HMRC's Digital Disclosure Service. If it involves income, assets or gains outside the UK, use the Worldwide Disclosure Facility.
Sources checked: 1 October 2026 · Sources are official GOV.UK pages.
This is general information, not tax advice for your situation. How it applies depends on your full circumstances.