How to Handle HMRC Investigations and Enquiries — A Founder's Guide (2026)

Types of HMRC Enquiries

1. Aspect Enquiry (S.9A TMA 1970) HMRC selects one or more specific items from your return for examination. Example: "We notice your R&D tax credit claim — please provide supporting documentation." Most common type. Lower stakes but must be taken seriously.

2. Full Enquiry HMRC examines your entire tax return — all figures, all claims. Triggered by significant inconsistencies, unusual patterns, tip-offs, or random selection. Significantly more time-consuming.

3. Code of Practice 9 (COP9 — Civil Investigation of Fraud) HMRC's most serious civil enquiry mechanism — used where HMRC suspects deliberate tax fraud. Involves a formal Contractual Disclosure Facility (CDF). Always use a specialist tax lawyer or accountant if you receive a COP9.

4. Compliance Check / Information Notice HMRC can issue Information Notices (Schedule 36 FA 2008) requiring you to provide documents and information. You must comply (with some exceptions) or face daily penalties.

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What Triggers an HMRC Enquiry?

HMRC uses risk-profiling software (CONNECT) that analyses returns and cross-references with other data sources (Companies House, Land Registry, bank data, overseas tax authority exchanges under CRS). Common triggers:

• Inconsistencies: Your turnover doesn't match VAT returns. Your dividend income doesn't match CT return.
• Unusual claims: R&D credits on a company with no apparent R&D activity. Very large expense deductions relative to turnover.
• Industry norms: Your profit margin is significantly below the industry average.
• Property: HMRC cross-references property purchases with declared income. If you bought a £1M house and your declared income doesn't support it, HMRC investigates.
• Random selection: HMRC runs random enquiry programmes — not all enquiries are risk-triggered.
• Tip-offs: Ex-partners, disgruntled employees, competitors. HMRC has a fraud reporting hotline.
• Third-party data: Overseas banks reporting accounts (CRS), payment processors reporting volumes.

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Your Rights During an HMRC Enquiry

Right to representation: You can appoint a tax advisor to handle all communications with HMRC. You are not required to speak to HMRC directly. Exercise this right immediately.

Right to know the reason: HMRC must tell you what aspect of your return is under enquiry in the opening enquiry letter. They cannot conduct a fishing expedition without specifying what they're investigating.

Right to refuse excessive requests: HMRC can formally request documents via an Information Notice. But not all requests are legally binding. An informal request ("could you provide X") has no legal compulsion. Even formal Schedule 36 notices have scope limitations — your advisor can challenge excessive or disproportionate requests.

Right against self-incrimination: You cannot be compelled to answer questions that would incriminate you in a criminal matter. In a civil enquiry, you must provide accurate information — but you retain the right to silence in criminal investigations.

• Time limits for HMRC enquiries:
• Opening an enquiry: HMRC must open within 12 months of the filing date for self-assessment / CT600 returns (the "enquiry window"). After this, HMRC can only enquire for older years in cases of carelessness (6 years) or deliberate understatement (20 years).
• Closing an enquiry: HMRC must issue a Closure Notice when the enquiry is complete. If they're dragging their feet, your advisor can apply to the tribunal for a direction to close.

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How to Respond Correctly

Step 1: Do not respond directly to HMRC. The opening enquiry letter will look official and urgent. Do not write back yourself. Appoint a qualified tax advisor (accountant or tax solicitor) and let them handle all correspondence.

Step 2: Gather your records. Collect all documentation related to the enquiry subject — invoices, bank statements, contracts, receipts. Organised records significantly speed up enquiries and demonstrate cooperation.

Step 3: Your advisor writes to HMRC. They acknowledge receipt of the enquiry, confirm representation, and set out the timeline for responding to any information requests. This buys time and establishes a professional tone.

Step 4: Provide accurate information. Never provide inaccurate information to HMRC — this escalates a civil enquiry to potential fraud investigation. If you made a mistake: disclose it voluntarily and promptly. Voluntary disclosure results in significantly lower penalties than HMRC-discovered underpayments.

Step 5: Negotiate settlement. Most enquiries are resolved by agreement — HMRC proposes an additional tax charge; your advisor negotiates it down to the defensible amount. Tribunals are a last resort (and expensive) but sometimes necessary if HMRC's position is unreasonable.

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Tax Investigation Insurance

Many accountants offer (or recommend) tax investigation insurance — covers professional fees incurred in defending HMRC enquiries. Cost: £150–400/year for most SMEs. Given that professional fees in a full enquiry can easily exceed £5,000–20,000, this insurance is extremely cost-effective.

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FAQs

Does receiving an HMRC enquiry mean I've done something wrong? No. Many enquiries are random or triggered by innocent anomalies. Receiving an enquiry is not a finding of wrongdoing. The enquiry is HMRC's opportunity to verify your return — and most enquiries are closed with no additional tax due.

How long does an HMRC enquiry take? Aspect enquiries: 3–12 months. Full enquiries: 6 months to 5+ years (for complex cases). The average full enquiry in the UK takes approximately 16 months from opening to closure.

Can HMRC search my home or office? Only with a search warrant (issued by a magistrate or High Court judge). HMRC cannot simply turn up and demand access. Warrants are sought in serious fraud cases — not routine compliance enquiries.

What penalties does HMRC impose if they find an underpayment? Penalties range from 0% (innocent error, proactively disclosed) to 100%+ of the unpaid tax (deliberate offshore non-compliance). The key factors: was it careless or deliberate, was it disclosed or discovered by HMRC, is it a domestic or offshore matter? Prompt voluntary disclosure significantly reduces penalties.

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