HMRC Compliance Checks

An HMRC compliance check is a review of your tax affairs to confirm you have paid the right amount of tax at the right time. Around 332,000 checks were opened in 2024-25 alone. Receiving one does not mean HMRC suspects fraud. This guide covers what triggers a check, how the compliance check process works in practice, your legal rights, and exactly what to do if a letter arrives.

What An HMRC Compliance Check Is (And How It Differs From An Enquiry Or Audit)

HMRC uses "compliance check" as an umbrella term covering tax enquiries, audits, and inspections across all UK taxes. The label applies whether HMRC is reviewing a self-assessment tax return, a corporation tax computation, a VAT return, or PAYE records.

A compliance check can happen before a return is filed (for example, checking record-keeping practices) or after submission as a formal enquiry into specific tax return figures. HMRC compliance checks can target genuine errors or misunderstandings of tax legislation; they are not reserved for suspected wrongdoing.

Most checks remain civil and routine. Only a small minority escalate to a criminal investigation, typically where deliberate tax evasion or forged documents are involved. Under Schedule 36 of the Finance Act 2008, HMRC can request documents and issue an inspection or information notice. Legal safeguards sit alongside these powers.

Compliance checks can target specific tax return aspects or be full enquiries. For example, a small design-and-manufacturing business might face a check on its R&D tax credit claims, requiring working papers, technical reports, and invoices. Another might be examined on corporation tax where expenses look high compared to sector benchmarks.

Why HMRC Starts A Compliance Check

HMRC uses both risk-based selection and random sampling, so any taxpayer can be checked. Over 90% of compliance checks are initiated due to information suggesting issues, rather than pure randomness.

Common risk triggers include:

• Large VAT repayment claims when turnover is low
• Repeated declared losses across multiple years
• Declared profits below sector averages
• Big year-on-year swings in income or turnover
• Corporation tax figures that do not match accounts filed at Companies House

HMRC uses data-matching to flag unusual taxpayer positions through its Connect system, which compares tax returns against employer reports, bank data, card processors, online marketplaces, and overseas tax authorities. Data mismatches occur when figures on a tax return disagree with third-party information. Compliance checks can be triggered by third-party information received from customers, suppliers, whistle-blowers, or other government departments.

Risk indicators include unusual trading patterns or mismatched data. Inconsistencies in income or unusual expense claims can trigger a compliance check. Repeated late filings of tax returns can also lead to a compliance check. High-risk sectors can attract compliance checks from HMRC. HMRC may check for inconsistencies between different tax returns.

For company directors: HMRC often scrutinises directors' loan accounts, benefits in kind, and unusually low salary combined with high dividend patterns. HMRC does not usually explain the precise trigger, and the absence of an explanation is normal.

Types Of HMRC Enquiries: Aspect, Full And Stand-Alone Compliance Checks

Not every HMRC compliance check covers the same ground. Scope ranges from a narrow look at one line item to a review of everything.

An aspect enquiry is limited to one or a few issues. HMRC might query VAT zero-rating on specific supplies, a particular expense category, or an R&D claim. The rest of the return is not under detailed scrutiny.

A full enquiry examines an individual's or company's whole tax return and underlying records for a tax year. All income streams, reliefs, deductions, and balance sheet items are in scope.

A stand-alone self assessment enquiry means HMRC is only reviewing a personal self assessment tax return. If you receive tax credits or Universal Credit, check how any proposed changes to your self assessment tax return might affect those claims.

HMRC can also run separate compliance checks into VAT, PAYE, Construction Industry Scheme, or corporation tax, sometimes in parallel. Compliance checks can vary in duration from weeks to months depending on complexity. Aspect enquiries with clear records may close in weeks; full enquiries often take 12 to 18 months. The broader the scope, the more documents and time are involved, and professional representation matters from the outset.

How HMRC Compliance Checks Work In Practice

Here is how compliance checks work, step by step.

Initial contact. HMRC sends a formal letter. That letter sets out the tax type (for example, corporation tax 2024/25), the periods under review, the compliance officer's name and contact details, and initial questions or an HMRC request for specific records. HMRC may send a formal letter notifying the start of a compliance check.

Information gathering. HMRC may follow up with an information notice under Schedule 36, require a meeting or call, or ask to visit business premises or your adviser's office. HMRC can request specific documents and may inspect business premises during checks. Requests for information during a compliance check typically have a strict deadline.

Records commonly requested include:

• VAT returns and tax calculations
• Corporation tax computations and accounts
• Bank statements
• Sales and purchase invoices
• Payroll and PAYE records
• Contracts and working papers supporting reliefs

Ongoing obligations. Continue to submit every tax return and pay ongoing liabilities. A compliance check does not pause your normal filing duties.

Outcome. HMRC will issue the result in writing. It might confirm you paid the right amount of tax, amend your assessment tax return, or issue an HMRC decision for extra tax plus interest and possibly a penalty. Compliance checks can lead to adjustments in tax returns. If you overpaid, expect a refund.

Record everything. Keep a dedicated folder (digital or physical) with copies of every letter, email, and notes of every phone call, including dates and the name of the HMRC officer you spoke to.

Your Rights, Safeguards And HMRC's Legal Powers

HMRC must use its powers reasonably, in line with the law and the HMRC Charter. You are not powerless.

A Schedule 36 information notice is a formal notice requiring you to produce documents or send information. A taxpayer notice goes to you directly; a third-party notice goes to a bank or other party. HMRC generally needs First-tier Tribunal approval to obtain records from third parties without telling you.

Key safeguards:

• Information must be "reasonably required" to check your tax position. You can challenge unreasonable information requests from HMRC.
• HMRC cannot demand legally privileged communications.
• Officers must respect statutory time limits when opening and closing enquiries.
• You have the right to understand what HMRC is checking. HMRC must provide clear explanations of their concerns.

Taxpayers have the right to be represented during compliance checks. You can appoint an accountant or tax adviser to deal with HMRC on your behalf, ask HMRC to clarify why specific documents are needed, and request extra support or more time if you have a reasonable excuse (illness, bereavement, disability).

You can appeal HMRC decisions within 30 days of notification. Options include requesting an internal review by a different HMRC officer or appealing to the First-tier Tribunal. You can also challenge a formal notice or an information notice if it is disproportionate. Taxpayers have 12 months to respond to HMRC's compliance check requests in some contexts, but 30-day deadlines are common for appeals.

Time Limits, Earlier Tax Years And Discovery Assessments

HMRC cannot reopen returns indefinitely. Statutory time limits depend on how serious any error is thought to be.

For a self-assessment tax return or company tax return filed on time, HMRC must open an enquiry within 12 months of the filing deadline. For example, a 2024/25 return filed by 31 January 2026 is open to enquiry until 31 January 2027.

After that window closes, HMRC relies on "discovery" powers to assess earlier tax years:

Escalation can involve extending reviews to earlier tax years once a pattern of under-declaration is identified. HMRC may issue broader Schedule 36 notices during escalation, and escalation may lead to detailed scrutiny of financial transactions. Serious inaccuracies can trigger civil fraud procedures by HMRC.

Voluntary disclosure before HMRC acts usually reduces penalties. Consider a company that under-declared corporation tax by £20,000 per year for four years. The underpaid tax alone is £80,000. Add statutory interest running from each original due date and a careless penalty of up to 30% of the amount of tax lost, and the total bill grows fast. Early and honest disclosure cuts both the penalty rate and the number of years in scope.

Penalties, Extra Tax And Managing Payment

If HMRC finds underpaid tax, they will charge interest automatically from the date the tax was originally due. HMRC may issue a tax assessment after a compliance check. Underpaid tax must be repaid with interest and penalties. Overpaid tax will be refunded along with any interest due.

Penalty bands work as follows. Penalties may be charged if inaccuracies are found during checks:

HMRC reduces penalties where a taxpayer tells HMRC about errors unprompted, gives full information, and helps calculate the correct figures. Cooperation throughout the process is the single largest factor in penalty reduction.

Keep paying any ongoing tax bill as normal. Once it looks likely that more tax will be due, start setting aside funds. The typical settlement is a schedule listing extra tax, statutory interest, and any penalty. Payment is usually due within 30 days. If you cannot pay in full, contact HMRC to request a payment plan (Time To Pay). Genuine engagement leads to more flexible terms than ignoring demands. You can ask HMRC for an internal review of penalties if you believe the rate is wrong.

Practical Steps When You Receive An HMRC Compliance Check Letter

If you have just opened an HMRC letter, work through these steps:

1. Confirm the letter is genuine. Check HMRC contact details against GOV.UK. Be wary of emails or texts requesting bank details. If in doubt, contact HMRC using a published number.
2. Note the deadline. Diarise the response date. If illness, bereavement, or other serious circumstances prevent a timely reply, ask HMRC for extra time in writing straight away.
3. Contact your accountant or tax adviser. Send them a full copy of the letter and any enclosures. Avoid calling HMRC substantively until you have taken specialist advice. Your adviser can deal with HMRC on your behalf.
4. Gather records. Begin collecting the documents HMRC has requested. Keep originals safe and provide clear copies or scans. Label files by tax year and tax type.
5. Flag any mistakes you spot. If you notice errors in your returns while pulling records together, discuss with your adviser whether to make an unprompted or prompted disclosure. Any explanation to HMRC should be consistent and evidenced. Telling HMRC about errors voluntarily before they find them tends to reduce penalties.
6. Set up a log. Record every phone call, email, and letter with dates, times, and the name of the hmrc officer involved. This log supports any future complaint or appeal.

Support, Representation And When Checks Escalate To Criminal Investigation

Compliance checks can be stressful, but formal support exists. HMRC offers extra support measures: giving more time, communicating via an authorised friend or family member, arranging shorter calls, or providing information in alternative formats for those with disabilities or mental health difficulties.

To authorise someone else to deal with HMRC, complete the relevant agent authorisation or write to HMRC giving permission for a specific named person to speak on your behalf for named taxes.

For complex checks involving multiple tax years, large sums, or cross-border issues, use qualified professional advisers with experience in tax investigations and tax disputes.

At a high level, HMRC opens a criminal investigation where there is suspected deliberate fraud, forged documents, or organised evasion. HMRC normally makes this status clear. Anyone told they are subject to criminal investigation, or invited to a formal interview under caution, should seek specialist legal representation immediately and avoid answering detailed questions without that advice.

If You Disagree With HMRC's Decision: Appeals, ADR And Complaints

You do not have to accept HMRC's conclusions. There is a structured process for anyone who wants to challenge HMRC.

• 30-day appeal window. Send a clear, dated letter or use the online tool setting out which hmrc decision you dispute and on what grounds. The 30-day clock starts from the date of the decision letter.
• Internal review or Tribunal. You can request an internal review by a different HMRC officer, or appeal to the First-tier Tribunal (Tax Chamber). Tax tribunals handle most tax disputes. Internal review can resolve matters without litigation.
• Alternative Dispute Resolution (ADR). ADR is a facilitative process run by trained HMRC staff, useful for complex factual or technical disputes. Using ADR does not remove your right to appeal.
• Closure direction. If you believe HMRC is taking too long without good reason, you can ask the Tribunal to order HMRC to close the enquiry by a specified date.
• Complaints. Complaints are separate from appeals. You can complain if HMRC delayed unreasonably, behaved discourteously, or failed to follow the HMRC Charter. In rare cases, compensation for serious maladministration is available.