Received a letter from HMRC? Discover why tax investigations happen, what HMRC can examine, how long checks can last and the steps you can take to protect your position.
What is an HMRC investigation?
An HMRC investigation is a review of your tax affairs to establish whether the correct amount of tax has been declared and paid. HMRC usually refers to this process as a compliance check or tax enquiry.
A check can involve an individual, sole trader, landlord, partnership or limited company. It may concern a single entry on a tax return or a much wider examination of business transactions, accounting records and tax calculations.
Receiving an investigation letter does not establish that you have underpaid tax or acted dishonestly. Some enquiries end without any adjustment.
HMRC normally identifies the tax or return being checked, requests relevant information and reviews the evidence. It may ask further questions before reaching a conclusion. If an error is identified, the result depends on the facts, applicable legislation and whether the error was reasonable, careless or deliberate.
Why does HMRC investigate someone?
HMRC uses information from tax returns, accounting records and other sources to identify possible discrepancies. Some checks are selected without an obvious error, while others arise because figures appear inconsistent or require explanation.
Unexpected figures
Income, expenses or profit margins appear unusual or inconsistent with other information.
VAT discrepancies
VAT returns, repayment claims or reported turnover raise questions.
Missing income
Declared income appears inconsistent with information HMRC holds.
Business expenses
HMRC questions whether deductions are allowable or supported by records.
Payroll and dividends
PAYE, benefits, director remuneration or dividend transactions need examination.
Routine checks
A return or tax position is selected for verification without necessarily implying wrongdoing.
What are the different types of HMRC investigation?
Aspect enquiry
A check concentrating on one or more particular items, such as an expense claim or income figure.
Full enquiry
A broader review covering the accuracy of a return and potentially several areas of the taxpayer's affairs.
Compliance check
A general term covering different HMRC checks, including VAT, Corporation Tax, PAYE and other tax obligations.
HMRC also has specialist civil investigation procedures for suspected fraud and separate criminal investigation powers. These are not the same as an ordinary compliance check. If a letter refers to Code of Practice 9, a Contractual Disclosure Facility or a criminal investigation, obtain specialist professional advice promptly.
What happens during an HMRC investigation?
The precise procedure depends on the type of tax and the legal basis of the enquiry, but many investigations follow five broad stages.
HMRC opens a check
You or your authorised agent receives a letter or other communication identifying the tax affairs under review. Read it carefully and check the response deadline.
Information is requested
HMRC may ask for invoices, bank statements, accounting records, explanations or supporting calculations. The request should be considered in light of the legal powers being used.
HMRC reviews the evidence
The officer compares information, raises questions and may request clarification or propose a meeting or visit. You can arrange for an accountant to assist.
Findings are discussed
HMRC may accept the original position, identify adjustments or consider whether penalties are appropriate. You should have the opportunity to explain disputed facts and calculations.
The enquiry is concluded
HMRC communicates its conclusion through the appropriate process. This may involve a closure notice, assessment, amendment, settlement or confirmation that no adjustment is required.
Received an HMRC investigation letter? What should you do?
The first response matters. Acting methodically can reduce misunderstandings, missed deadlines and unnecessary work.
- Check authenticity. Verify the letter or call using independently obtained HMRC contact details. Do not rely solely on links or telephone numbers in an unexpected message.
- Identify the enquiry. Record the tax, period, case reference, officer and response deadline.
- Read the legal basis. Determine whether the letter is an informal request, formal information notice or statutory enquiry.
- Preserve relevant records. Keep original documents and electronic information. Do not alter or destroy evidence.
- Review the position. Reconcile returns, accounts and supporting documents before answering substantive questions.
- Seek advice where appropriate. An accountant can help with records, calculations and correspondence; specialist tax or legal representation may be necessary in serious cases.
- Respond within the deadline. If more time is genuinely needed, contact HMRC promptly to request an extension.
If the investigation concerns a submitted return, our guide to the amendment of a tax return explains the wider correction process. Do not assume that an ordinary amendment is the correct way to deal with a return already under enquiry.
What rights do you have during an HMRC investigation?
HMRC has significant information and inspection powers, but those powers are subject to statutory conditions and safeguards.
Professional representation
You can appoint an accountant or other suitable adviser to communicate with HMRC on your behalf.
Reasonable requests
You can question whether requested information is relevant, reasonably required or legally protected.
Dispute and appeal
Some formal notices, assessments and penalties carry review or appeal rights, subject to the applicable rules and deadlines.
You also have responsibilities. These can include retaining appropriate records, supplying information lawfully required and cooperating with valid notices.
An informal request is not necessarily the same as a statutory information notice. A meeting request, premises inspection or formal notice may have different rules. Never ignore a formal notice simply because you disagree with it; obtain advice on the appropriate response or appeal route.
What documents can HMRC ask to see?
Requests vary according to the issues under investigation. Relevant documents may include:
Financial records
Bank statements, sales invoices, receipts, ledgers, bookkeeping exports and reconciliations.
Tax information
Tax returns, VAT workings, payroll records, Corporation Tax calculations and supporting schedules.
Supporting evidence
Contracts, mileage logs, expense explanations, asset records and relevant business correspondence.
HMRC cannot automatically demand every document without restriction. The relevance of the information, applicable statutory powers, third-party material and legally privileged communications may all matter.
For limited companies, maintaining accurate company accounts and Corporation Tax filings helps ensure transactions can be explained consistently.
How far back can HMRC investigate?
A common question is whether HMRC can look back four, six or twenty years. The answer depends on the tax, the circumstances and the legal procedure involved.
| Period | Typical circumstances | Important qualification |
|---|---|---|
| 4 years | Normal assessment time limit | Generally measured from the end of the relevant tax period, subject to tax-specific rules. |
| 6 years | Certain tax losses arising from careless behaviour | Applies only where the relevant statutory conditions are met. |
| 12 years | Certain offshore income, gains or transfers | Special rules and exceptions apply; this is not a general time limit for all taxes. |
| 20 years | Certain deliberate inaccuracies or failures | Requires the relevant legal conditions to be satisfied. |
What happens if HMRC finds a mistake?
The outcome is based on the evidence and the relevant tax rules. Broadly, there are three possibilities.
No adjustment
HMRC accepts the position and concludes the check without additional tax being due.
Tax adjustment
An underpayment may result in additional tax and interest. An overpayment may lead to a repayment.
Penalty consideration
HMRC may consider penalties where the statutory conditions are met, taking account of behaviour and disclosure.
Are HMRC investigation penalties automatic?
No. An error does not automatically mean a penalty is payable. The penalty regime depends on the type of failure, the applicable legislation, the taxpayer's behaviour and any available reductions.
For inaccuracies under the relevant behaviour-based regime, the distinction between reasonable care, carelessness and deliberate behaviour can be particularly important. Prompt, accurate and complete cooperation can affect the reduction available where a penalty applies.
Can HMRC prosecute you?
Most routine compliance checks are civil matters. HMRC can pursue criminal investigations in serious cases, including suspected tax fraud. A routine enquiry letter does not mean criminal proceedings are underway.
What if you cannot afford the additional tax?
Contact HMRC promptly about your circumstances. A payment arrangement may be possible depending on eligibility and affordability. Our HMRC Time to Pay guide explains the options and considerations.
What if you disagree with HMRC?
You may be able to request a statutory review, appeal to the tax tribunal or use alternative dispute resolution, depending on the decision and circumstances. Formal appeal deadlines can be short, so read the decision notice carefully and obtain advice promptly.
HMRC Investigation Response Checklist
Use this practical checklist to organise your initial response. Tick each action as you complete it, then copy a summary for your own records.
Your investigation preparation tracker
A simple planning tool. No personal or tax information is requested or transmitted by this checklist.
0 of 8 actions completed
HMRC Investigation FAQs
Does an HMRC investigation mean I have done something wrong?
No. HMRC may check a tax return to verify figures or clarify information. The opening of a check does not establish an error or wrongdoing.
How do I know if HMRC is investigating me?
HMRC will normally notify you or your authorised agent about a compliance check. The communication should explain what is being checked. Independently verify unexpected correspondence.
Can HMRC check my personal bank account?
Personal banking information may be relevant to certain tax enquiries, particularly where personal and business transactions overlap. HMRC's access to information is governed by legal powers and safeguards; it does not have unrestricted access in every case.
Can HMRC investigate a dissolved limited company?
Dissolution does not necessarily prevent HMRC from examining historic tax liabilities or taking available legal action. The circumstances, applicable time limits and company status require individual assessment.
Can HMRC visit my home or business?
HMRC may request a meeting or inspection. Different rules apply to voluntary visits, formal inspections, business premises and private dwellings. Obtain advice if you are unsure about the legal basis or your rights.
Do I have to attend an HMRC meeting?
Not every requested meeting is compulsory. The position depends on the circumstances and statutory powers being used. You can ask for the purpose of the meeting and arrange suitable representation.
How long does an HMRC investigation last?
There is no fixed duration for every compliance check. Complexity, available records, correspondence and disputed issues can affect how long it takes.
Can HMRC investigate after accepting my tax return?
Acceptance or processing of a return does not necessarily prevent a lawful enquiry or assessment. The relevant statutory time limits and conditions must be considered.
What happens if I ignore an HMRC investigation letter?
Ignoring correspondence can lead to escalation, formal information notices and potential penalties. Verify the letter and respond appropriately, even if you need to request more time.
Can I change accountants during an HMRC investigation?
Yes. You can appoint a new accountant while an enquiry is ongoing. Ensure records, correspondence, authority and deadlines are transferred properly. Read our guide to changing accountants.
Can an accountant stop an HMRC investigation?
An accountant cannot guarantee that HMRC will close a lawful investigation. They can help explain the tax position, organise evidence, challenge inappropriate requests and work towards a properly supported resolution.
Will I have to pay a penalty if HMRC finds an error?
Not necessarily. The applicable penalty rules depend on the circumstances, including the type of error, reasonable care, behaviour and any available reductions.
How an accountant can help during an HMRC investigation
Professional support can be valuable when the enquiry involves complex transactions, incomplete records, substantial tax exposure or disputed calculations.
An accountant may help you review the correspondence, reconstruct accounting information, identify errors, prepare calculations and communicate clearly with HMRC. Cases involving suspected fraud, Code of Practice 9 or criminal proceedings may require specialist tax investigation and legal advisers.
At The Online Accountants, our ACCA-qualified team supports UK businesses with accounting, tax compliance and financial reporting. We can discuss your circumstances and explain whether we can assist directly or whether specialist representation would be more appropriate.
Concerned about an HMRC investigation?
Get clarity on your next steps. Contact The Online Accountants to discuss your tax and accounting requirements.
Related tax and accounting guides
HMRC Time to Pay
What to consider if you need more time to pay a tax liability.
Amending a Tax Return
Understand the process for correcting submitted tax information.
What Is a CT600?
Learn how limited companies report Corporation Tax liabilities.
HMRC Business Tax Account
Understand how businesses access and manage their HMRC information.
How to Change Accountants
Steps to appointing a new accountant and transferring records.
Our Fixed Accounting Fees
Explore our accounting and tax compliance services.
Reviewed for November 2026. General UK tax information only, not personalised tax or legal advice. Enquiry powers, assessment limits, penalties and appeal procedures vary by tax and circumstance. The Online Accountants is a trading name of Parkinson (UK) Limited.