Answers · UK 2025/26
What are HMRC's enquiry and investigation powers in the UK for 2026?
HMRC can open a formal enquiry into a Self Assessment return within 12 months of the filing date (or longer for fraudulent or negligent returns). HMRC has extensive information-gathering powers including Schedule 36 notices to produce documents, third-party notices to banks and advisers, and the ability to make discovery assessments for underpaid tax going back 4-20 years depending on behaviour.
Full answer
HMRC's enquiry, investigation, and assessment powers are set out primarily in TMA 1970, Schedule 36 FA 2008, and FA 2007/2008 penalty provisions. **Formal enquiry into a Self Assessment return (TMA 1970 s.9A):** HMRC can open an enquiry into any Self Assessment return within: - **12 months** of the filing date if the return was filed on time - **12 months from actual filing** if filed late The enquiry must be opened by formal written notice. HMRC can enquire into anything on the return. **Discovery assessments (TMA 1970 s.29):** After the 12-month enquiry window closes, HMRC can still issue a "discovery assessment" if they discover additional tax is owed: - **4 years** from end of the tax year for careless or innocent error - **6 years** for careless behaviour - **20 years** for deliberate (fraudulent) non-disclosure **Schedule 36 information and inspection powers (FA 2008):** - HMRC can issue a Schedule 36 notice requiring a taxpayer to produce documents or provide information - Third-party notices can be served on banks, accountants, solicitors, and other parties to obtain information about a taxpayer - Penalties of up to £300 plus £60/day apply for non-compliance **Compliance checks vs criminal investigation:** Most HMRC enquiries are civil compliance checks. Criminal investigation (using PACE powers, prosecution) is reserved for the most serious cases of deliberate fraud. HMRC's Fraud Investigation Service (FIS) handles the criminal route. **Taxpayer rights:** - You can appeal against HMRC's conclusions to the First-tier Tax Tribunal - You have the right to seek Statutory Review by an independent HMRC officer before appealing - HMRC must follow the Litigation and Settlement Strategy (LSS) in resolving disputes **Penalty regime:** Penalties for incorrect returns range from 0% (innocent error, prompted disclosure) to 200% (deliberate and concealed, offshore) depending on behaviour, territory, and whether the error was prompted or unprompted.
Try the calculator
This answer is informational only and does not constitute financial, tax or legal advice. Figures are for the 2025/26 UK tax year. See our methodology and sources.