HMRC Tax Compliance Check Guide UK (Investigation 2026)

Why HMRC Selects You for a Compliance Check

HMRC uses a sophisticated computer system called Connect to analyse vast amounts of data and identify taxpayers whose returns look unusual or risky. Connect cross-references data from multiple sources: your tax returns, bank account interest reports, property transactions from the Land Registry, company filings from Companies House, credit card data, PayPal and eBay transaction information, and even social media in some cases. Common triggers for a compliance check include: significant fluctuations in income compared to previous years; expenses that seem high relative to your income (especially in trades like construction, taxi driving, or hairdressing where cash income is common); claims for large refunds; inconsistencies between personal and business accounts; late filing or payment history; industry-specific risk factors (certain sectors like property, construction, and hospitality are more likely to be checked due to higher perceived non-compliance); and random selection — HMRC also selects a proportion of returns purely at random to maintain a deterrent effect and to test compliance across all demographics. You are also more likely to be selected if you have been investigated before and errors were found, or if a third party (such as a former employee, business partner, or ex-spouse) provides information about you. Being selected is not an accusation — it is a routine check. However, if HMRC suspects deliberate evasion, the check can escalate into a full criminal investigation, which is a different and more serious process.

Types of Checks (Aspect, Full, Random)

HMRC compliance checks fall into three main categories depending on the scope and the reason for the check. Aspect enquiry: this is the most common type. HMRC focuses on one or more specific aspects of your return — for example, your rental income, capital gains, or a particular expense claim. The letter will state clearly which aspects are being reviewed. You only need to provide information relevant to those aspects. Aspect enquiries are usually resolved within 3–6 months. Full enquiry: HMRC reviews your entire tax return — all income, expenses, gains, and reliefs claimed. This is more comprehensive and typically takes 6–12 months, sometimes longer. Full enquiries are more common for businesses, complex returns, or when there are multiple risk indicators. Random check: HMRC randomly selects a small percentage of returns each year as part of its compliance monitoring. These are genuine random selections — you have not been flagged for any specific reason. Random checks can be aspect or full enquiries. They are designed to gather data on overall compliance levels and maintain a deterrent effect. Regardless of the type, HMRC must issue a formal notice in writing (a "Section 9A notice" for Income Tax or "Schedule 36 notice" for VAT and other taxes) before starting the check. The notice will specify the tax year(s) under review and the records they require. You have the right to know what is being checked and why. If HMRC tries to escalate an aspect enquiry into a full enquiry without reasonable grounds, you can challenge the scope through your tax adviser or by writing to HMRC.

What HMRC Can Ask For (Records, Accounts, Bank Statements)

HMRC has broad legal powers to request information and documents relevant to the compliance check. They can ask for: bank statements (personal and business) covering the period under review; business accounts and invoices (sales invoices, purchase invoices, receipts, contracts); proof of expenses claimed on your tax return; payroll records if you employ staff; VAT records if you are VAT-registered; rental records if you are a landlord; share transaction records if you have capital gains or losses; dividend vouchers and investment income records; and personal financial statements (including details of gifts received, loans, or inheritance). HMRC can also request information from third parties — your bank, your accountant, your tenants, or your business partners — but they must notify you first and give you a chance to object. You must provide the requested information within a reasonable timeframe (usually 30 days). Failure to comply without a reasonable excuse can result in a penalty of £300 initially, plus £60 per day for continued non-compliance. If you cannot provide certain records (for example, they were lost in a fire or flood), tell HMRC immediately — they may accept alternative evidence. Right to professional advice: you can appoint a tax agent (accountant or tax adviser) to handle the compliance check on your behalf. HMRC must correspond with your agent if you authorise them. You are not required to answer questions without your adviser present. If you are unsure about any request, ask your adviser before responding. HMRC cannot force you to answer questions that may incriminate you (the privilege against self-incrimination), but this protection is limited in tax matters and does not apply to document requests.

Your Rights During a Tax Check

You have important rights during an HMRC compliance check that are designed to ensure the process is fair and proportionate. Right to be informed: HMRC must tell you in writing what they are checking, which tax years, and what information they need. Right to a reasonable timeframe: you must be given at least 30 days to provide information. Right to professional representation: you can have a tax adviser handle all communications with HMRC. Right to appeal: if you disagree with HMRC's information request, you can appeal to the First-tier Tribunal (Tax Chamber). HMRC cannot impose penalties for non-compliance while an appeal is pending. Right to remain silent: you are not obliged to attend a face-to-face meeting with HMRC, though they may request one. You can refuse and insist on written correspondence only. Right to claim privilege: legal professional privilege (communications with your solicitor) and the privilege against self-incrimination (you do not have to answer questions that might incriminate you) apply, though their scope is narrower in tax investigations than in criminal cases. Right to complain: if HMRC behaves unreasonably (excessive demands, unreasonable delays, aggressive tactics), you can complain through HMRC's complaints process and then to the Adjudicator's Office or Parliamentary Ombudsman — see our Complain about HMRC guide →. Right to judicial review: in extreme cases where HMRC acts unlawfully, you can apply for judicial review. You should never lie or deliberately provide false information — this can turn a civil check into a criminal investigation for tax evasion. Always seek professional advice if you are unsure how to respond to any request from HMRC.

How Long a Compliance Check Takes

The duration of an HMRC compliance check depends on the complexity of the issues and how promptly you respond. Simple aspect enquiries: typically resolved within 3–6 months of the initial letter. If you provide the requested information quickly and there are no complications, HMRC may close the check within a few weeks. Full enquiries: these take longer — usually 6–12 months, sometimes up to 18 months for complex cases involving businesses, multiple years, or disputed issues. Very complex cases: involving large amounts of tax, offshore structures, or potential deliberate evasion can take 2 years or more, especially if they involve litigation or criminal investigation. HMRC has a statutory time limit for opening a compliance check. For Income Tax and Capital Gains Tax, they must generally open the check within 12 months of the filing deadline. For example, for the 2024/25 tax year (filing deadline 31 January 2026), HMRC must open a check by 31 January 2027. There are exceptions: if HMRC suspects fraud or if the return was filed late, the time limit can be extended. You can speed up the process by: responding promptly (within the 30-day window), providing complete and well-organised information, engaging a tax adviser if the issues are complex, and being transparent about any errors rather than hoping they will not be found. If HMRC is unreasonably slow, you can ask them to explain the delay and, if necessary, complain through the HMRC complaints process. Prolonged uncertainty can be stressful — a good tax adviser can manage the timetable and keep HMRC accountable.

What Happens If HMRC Finds an Error

If HMRC concludes that your return was wrong, they will issue a closure notice setting out the adjustments to your tax liability. The outcome depends on the nature of the error. Careless error: if you failed to take reasonable care (missed a source of income, claimed a deduction you were not entitled to), HMRC will assess the additional tax due plus interest. A penalty of 0% to 30% of the extra tax may apply, depending on how quickly you disclose and correct the error. If you voluntarily disclose before HMRC raises the issue ("unprompted disclosure"), the penalty range is 0% to 15%. If HMRC discovered the error first ("prompted disclosure"), the penalty range is 15% to 30%. Deliberate error: if you knowingly understated income or overstated expenses, the penalty range is 20% to 100% (unprompted disclosure) or 35% to 100% (prompted disclosure). Deliberate and concealed: if you took active steps to hide the error (false invoices, hidden bank accounts), the penalty can be up to 200% of the extra tax. No error: if the check finds your return is correct, HMRC issues a closure notice stating that no adjustments are needed. You do not owe any additional tax, and you may be entitled to claim your reasonable costs of dealing with the check (in limited circumstances). If you disagree with HMRC's findings, you can appeal to the First-tier Tribunal (Tax Chamber) within 30 days. You can also request a review by an independent HMRC officer before going to tribunal. Most compliance checks are resolved by agreement without formal appeals — your tax adviser will usually negotiate the outcome with HMRC's compliance officer. For serious cases of deliberate evasion, HMRC may pursue criminal prosecution, though this is rare and reserved for the most serious cases of fraud.

FAQs

Can HMRC access my bank accounts without telling me?

HMRC can issue a third-party notice to your bank requesting account information. They must notify you of the request and give you 30 days to object. In cases of suspected fraud, HMRC can obtain a tribunal order without notifying you in advance.

Can I be investigated twice for the same tax year?

No. Once HMRC issues a closure notice concluding a compliance check, they cannot normally reopen the same year unless they discover fraudulent or negligent conduct that was not previously disclosed. Each year is treated separately.

Should I use a tax adviser during a compliance check?

Yes, if you are unsure about any aspect of the process. A qualified tax adviser (chartered accountant or tax specialist) can handle communications, ensure your rights are protected, negotiate penalties, and often achieve a better outcome than dealing with HMRC alone.

What if I cannot find the records HMRC is asking for?

Tell HMRC immediately and explain why the records are unavailable (lost, destroyed, never existed). HMRC may accept alternative evidence such as bank statements, third-party confirmations, or your own sworn statement. Do not fabricate records — that is a criminal offence.

How far back can HMRC investigate?

Normally 4 years for careless errors, 6 years for deliberate errors, and up to 20 years for deliberate and concealed errors. HMRC can go back further if they suspect fraud. The time limits run from the end of the tax year in which the return was filed.