If you receive an HMRC investigation letter, first establish what HMRC is checking, note the response deadline and gather the relevant records. Do not ignore the letter or send a rushed explanation based on incomplete information.
A clear, evidence-based response starts with understanding the request. An HMRC letter does not automatically mean you have committed an offence or owe extra tax.
It may concern a particular figure, a return or a wider compliance check. What matters is the wording of your letter, the tax and period involved, and whether it includes a formal notice.
Have a letter in front of you? Note its reference, deadline and requested documents before preparing your reply.
This guide explains your immediate steps, which records to prepare, what to avoid and when specialist representation can help.
If the letter is unexpected, check it against HMRC’s guidance on genuine letters. If you remain unsure, verify the contact through an independently obtained GOV.UK contact route before sending financial information. Do not rely only on a telephone number or link in suspicious correspondence.
Keep a copy of the letter and attachments, and add the deadline to your calendar. There is no single response period for every HMRC investigation letter: use the deadline stated in your correspondence. If you cannot provide everything in time, contact the officer promptly, explain what is missing and ask whether more time can be agreed. Do not assume an extension has been granted.
List the tax, accounting period, figures and documents mentioned. Distinguish between an initial request and a formal information notice. An information notice is a legal requirement, and the notice explains any available appeal rights. If you disagree with a request, seek advice on the proper response rather than ignoring it.
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Preserve the original records and collect the material relevant to the request. Build a simple index linking each question to its supporting documents. Where a figure does not reconcile, identify the difference before presenting an explanation. Separate confirmed facts from matters that still need checking.
Your regular accountant may already hold the records and be able to help. Specialist support is particularly useful when the enquiry covers several taxes or years, material discrepancies, disputed penalties or allegations of deliberate conduct. Agree who will coordinate correspondence so HMRC receives a consistent response.
If you need help interpreting the letter, Apex Accountants’ HMRC tax investigation service can help you assess the request and plan your response.
The letter should guide your document collection. This checklist is a starting point, not a requirement to send every record you hold.
If records are unavailable, explain the gap to your adviser and explore legitimate ways to obtain copies. Do not fabricate documents or alter originals. For wider company record-keeping guidance, see records a limited company should keep.
HMRC may ask questions, request further documents or arrange a meeting or visit. You can have an accountant or legal adviser with you during a visit. The process may develop as evidence is reviewed, so keep a record of requests, replies and agreed actions.
At the end of a check, HMRC tells you the result. Depending on the findings, there may be no additional liability, a repayment, or additional tax, interest and potentially penalties. Do not assume a particular outcome simply because an investigation has begun. HMRC’s compliance-check guidance explains the process.
For more detail, see our guides to common investigation triggers and investigation duration and time limits.
A penalty is not an automatic consequence of receiving a letter. If an inaccuracy is found, the applicable rules depend on the tax, circumstances and behaviour involved. HMRC distinguishes between errors despite reasonable care, careless inaccuracies and deliberate behaviour.
For inaccuracies covered by HMRC’s CC/FS7A guidance, disclosure and assistance can affect the penalty calculation. A disclosure made after HMRC has contacted you may be treated differently from an unprompted disclosure. Your adviser should assess the actual rules rather than apply one percentage to every case. See HMRC’s penalties factsheet.
A Code of Practice 9 (COP9) letter needs specialist attention. Under COP9, HMRC suspects a loss of tax through deliberate behaviour and may offer the Contractual Disclosure Facility (CDF). This is different from an ordinary request to clarify a return.
HMRC provides a 60-day period from receipt of the CDF offer to respond. The choice and disclosure requirements have significant consequences. Obtain specialist advice promptly rather than using a standard response letter. Read HMRC’s COP9 guidance.
An adviser can interpret the letter, organise supporting evidence, check reconciliations and handle correspondence within the agreed engagement. HMRC requires appropriate authorisation to deal with an adviser on your behalf; its current compliance-check guidance refers to form COMP1a. Appointing an adviser does not remove your responsibility for your tax affairs. See HMRC’s agent-authorisation guidance.
Rana’s background includes a period working within HMRC followed by many years advising individuals and businesses on enquiries and investigations. His experience covers VAT, PAYE, Corporation Tax, Personal Tax, property, Capital Gains Tax, overseas income and overseas assets.
Apex Accountants can help you understand the correspondence, prepare your position and manage the enquiry. For VAT-specific concerns, see our HMRC VAT investigation and dispute support.
No. A letter may ask you to clarify information or allow HMRC to check a return. Read the scope before drawing conclusions.
Work to the deadline in your letter. If you need more time, raise this promptly and confirm whether an extension is agreed. Different notices can have different rules.
Yes, where the necessary authorisation and engagement are in place. Make sure your accountant has the complete letter and supporting records.
Preserve the evidence, establish what happened and discuss the appropriate correction or disclosure with your adviser. The procedure depends on the tax, timing and circumstances.
There may be appeal or review rights. Many tax decisions have a 30-day deadline, but use the instructions in the decision letter and obtain advice on your case. GOV.UK explains tax appeals and reviews.
No. Advice can help you present accurate evidence and address issues, but the outcome depends on the facts and applicable rules.
Start with the letter, its deadline and the relevant records. Book a consultation with Apex Accountants to discuss what HMRC is asking and the support you need.
General guidance checked against the linked HMRC sources on 6 October 2026. The wording and deadlines in your own correspondence should guide your response.
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