HMRC Compliance Check Explained: Tax Investigation Letters, Your Rights and What to Do

What an HMRC compliance check actually is

HM Revenue & Customs uses compliance checks to establish whether taxpayers have accounted correctly for tax, claimed appropriate reliefs and kept the necessary records. A review may be narrow—for example one expense category—or may involve a wider investigation into a Self Assessment return, Company Tax Return, VAT returns, PAYE, CIS or other taxes.

The opening letter should identify the subject and give information about the check. HMRC may work through correspondence or telephone enquiries, request documents, or arrange a visit where legally appropriate. The relevant legal powers and taxpayer protections differ by tax and type of request.

A check is not a court finding and not proof of evasion. Equally, it is not safe to treat the letter as routine marketing. Read it as a real procedural event with a defined scope and potential consequences if ignored.

First 24 hours: what to do after receiving the letter

1. Check authenticity. Independently verify the HMRC contact using official GOV.UK channels rather than an unexpected phone number or link.
2. Identify the tax. Record the tax type, business or UTR/VAT reference, accounting period and named caseworker.
3. Calendar the deadline. Use the actual date written in the letter; do not assume there is a universal 30-day response period.
4. Preserve the evidence. Keep accounting records, emails, invoices and bank statements in their original form.
5. Identify the request type. An informal information request is different from a formal statutory information notice or a decision.
6. Decide who responds. Confirm HMRC agent authorization and agree roles with your accountant or tax adviser.

Only after these six steps should you prepare a response. If you think the letter is fraudulent, do not use its links, QR codes or payment instructions; seek confirmation from published HMRC contact information.

The three documents people commonly confuse

The label and legal footing matter. A person may be cooperative while still asking HMRC to explain why material is reasonably required. Conversely, refusing a valid statutory notice without a proper basis can lead to penalties. Keep a copy of all correspondence.

What HMRC can ask for

Depending on the check, HMRC may seek invoices, receipts, contracts, bank and credit-card statements, bookkeeping exports, payroll records, VAT calculations, mileage logs, director-loan entries, rental-property statements or supporting documentation for tax reliefs. A focused enquiry may ask for only one item; a wider check may require a period of records.

HMRC’s information powers are subject to legal limits. A taxpayer notice may cover statutory records and other information reasonably required to check a person’s tax position, with particular appeal rules depending on the item demanded. Not everything in a business file is automatically relevant simply because a check exists.

Organize documents around the transactions or questions in the letter. Redact or restrict unrelated personal information only where lawful and appropriate; do not alter source records or quietly recreate missing invoices to look historical.

An effective evidence pack: eight folders

Do not upload unnecessary sensitive data to an ordinary email chain. Agree an approved secure transfer method; existing clients can use the Britvex client portal for appropriate communications and document-management steps.

How to answer HMRC accurately and professionally

A strong reply answers each question in the same order it appears in HMRC’s correspondence. State the accounting period, taxpayer reference where appropriate, facts you have verified, supporting documents and any information still being gathered. If a question seems broader than the stated issue, ask for clarification before supplying disproportionate materials.

Distinguish an explanation from an estimate: if a historical record is missing, describe what you can substantiate and how you reconstructed the figure from reliable evidence. Do not sign a statement you have not checked. A concise factual chronology is often more useful than a long defensive letter.

If a deadline cannot reasonably be met, communicate before it expires and propose a realistic schedule. HMRC may agree additional time in appropriate cases; that is not automatic and should be confirmed in writing.

Illustrative case: unexplained bank deposits

Imagine a small company receives a request to explain £18,000 of credits in its bank account that do not immediately match declared turnover. The accounts team discovers £9,000 was customer sales already included through a payment provider, £5,000 was a documented director loan and £4,000 was an inter-account transfer.

The useful response is not merely “these are not sales.” It is a reconciled schedule showing each credit, date, counterparty, original invoice or loan record, the corresponding ledger entry and the tax treatment. Where entries were booked incorrectly, corrections may be required. The example demonstrates why documented explanations matter more than a general reassurance.

It is fictional and does not determine the treatment of any real transaction; director loans, VAT and turnover recognition can introduce additional issues.

Illustrative case: an excessive expense claim

A sole trader claims £7,000 of travel costs. HMRC queries an unusually high proportion relative to turnover. On review, the records identify £4,900 of qualifying business travel, £1,200 of ordinary commuting or private travel, and £900 with insufficient evidence.

A sensible process checks the original claim against the rules, seeks missing support where it exists, prepares a corrected calculation if warranted and explains the error accurately. Tax due, interest and any penalty consideration are separate questions. Do not assume an innocent error can always be dismissed, or that a penalty is inevitable. HMRC examines the circumstances and behaviour.

Your rights during a compliance check

You may ask HMRC to explain the basis and scope of a check, appoint an authorized adviser, request appropriate support and ask questions about information sought. HMRC should explain the applicable factsheets and rights when checks begin or formal powers are used. There can be legal restrictions or special processes for documents, visits and statutory notices.

Taxpayers may have review or appeal rights against particular decisions. They do not necessarily have a general right to refuse every record request. The correct legal response to an information notice should be assessed on that notice’s wording and the statutory records involved.

Consult HMRC factsheet CC/FS1a and, for complex cases, seek professional legal or tax advice promptly.

What about a visit, meeting or interview?

HMRC can sometimes arrange visits and inspections under applicable rules. Ask whether a visit is by agreement or under formal authority, what records the team expects, whether the premises and tax periods are correct and who will attend. You can generally have an accountant or legal adviser with you, according to HMRC’s public guidance.

Prepare a quiet place, indexed records, a clear contact person and notes of what has been asked and supplied. Do not coach employees to misstate facts or withhold documents improperly. Equally, a responsible adviser can ensure the visit stays proportionate to the disclosed scope.

Penalties, interest and repayments: do not mix them up

A compliance check may result in no change, a repayment, additional tax, interest or penalties depending on the findings. These are distinct. Interest generally reflects time value when tax was late; a penalty can reflect the nature of an error or failure and may depend on behaviour, cooperation, disclosures and the legal regime.

Penalties for failure to comply with a valid information or inspection notice may arise separately from penalties for inaccurate returns. There is no universal percentage penalty for every HMRC check, and a check itself does not mean a fine will be charged.

Where HMRC determines additional tax is due after a check, its public guidance says payment is generally requested within 30 days; speak to the officer promptly if payment is difficult. Check the actual demand for the applicable date.

Disagreeing with HMRC: appeal, review and ADR

If you disagree with a formal decision or penalty, read the decision letter. HMRC says the time limit to appeal or accept a review is usually 30 days from the date of the decision letter, but the exact rights and route depend on the tax and type of decision. Do not assume an opening compliance letter has this same appeals deadline.

For direct taxes, you would normally appeal to HMRC first. A statutory review may follow; tax tribunal proceedings can be available where the legal conditions are met. Alternative dispute resolution may be appropriate in certain cases, but it is not a substitute for protecting a formal appeal deadline.

Our tax services and company compliance support can help clients organize the financial evidence needed to understand a dispute, within an agreed engagement scope.

What a representative can and cannot promise

An accountant or tax adviser can help reconcile records, prepare responses, confirm tax computations and correspond with HMRC where properly authorized. Some disputes call for a specialist tax dispute practitioner or lawyer. Support is not the same as guaranteeing the check will close, eliminating penalties or promising a particular settlement.

Ask any adviser who will handle the matter, what experience applies to the tax involved, whether the quoted fee covers meetings and formal appeal work, and how sensitive documents will be protected. An adviser should also explain what information may need to be corrected rather than simply defending every submitted figure.

How to reduce future compliance risk

Tax compliance is easier when an audit trail is assembled during ordinary operations rather than after a letter arrives. Reconcile banks monthly, retain invoices and payroll records, document director transactions, review expense policies and track VAT and Corporation Tax calculations before filing.

For businesses using digital accounting tools, maintain consistent source documents and controlled changes to bookkeeping data. Our bookkeeping services can support routine records and management reporting; our portal allows clients to coordinate documents with the team.

A stronger process does not make HMRC enquiries impossible, but it can make a proportionate and accurate response substantially easier.

Getting help from Britvex

Britvex can review an HMRC letter, identify the accounting and tax information requested, discuss the relevant response timeline and agree an appropriate scope of support. We do not describe every enquiry as a crisis. Often the first requirement is to identify the facts and retrieve a clean set of records.

Send a confidential enquiry to info@britvex.co.uk, call +44 20 3758 7500, or use the client portal help and support if you already work with Britvex. Avoid sending sensitive tax records through open social-media messages.

Frequently asked questions

Official UK references and further reading

The guidance below is the regulatory starting point for figures, procedural rights and thresholds discussed here. Specific tax positions require an individual review.

• GOV.UK — Tax compliance checks
• HMRC — About compliance checks CC/FS1a
• HMRC — Asking for information CH207330
• HMRC — Taxpayer information notice CH223200
• GOV.UK — Disagree with tax decision
• GOV.UK — Statutory review
• GOV.UK — Compliance check factsheets