How to Handle HMRC Investigations and Tax Enquiries

Receiving a letter from HMRC about your tax return is unsettling, but it does not always mean serious trouble. HMRC opens different types of enquiries for different reasons — some are random compliance checks, others are targeted because something in your return triggered a query. Understanding the process and your rights will help you respond appropriately.

Types of HMRC Enquiry

Full Enquiry

HMRC examines your entire tax return for the year in question. This is more likely for complex tax affairs or where HMRC suspects a significant understatement.

Aspect Enquiry

HMRC focuses on a specific element of your return — for example, your self-employment income, a particular expense, or capital gains. This is the most common type and often resolves quickly.

Compliance Check

A broader check of your records and business practices, which may not be tied to a specific return.

The Opening Window

HMRC can normally open an enquiry within 12 months of the date you submitted your tax return. If your return was filed late, the window extends to 12 months from the filing date. For suspected fraud, HMRC can go back 20 years. For careless errors, they can investigate up to 6 years back.

Your Rights

You have the right to be told which period is being examined and which aspects are in question. You have the right to professional representation — an accountant or tax adviser can handle all communication with HMRC on your behalf. You are not obliged to attend meetings with HMRC officers without representation. Any information you provide voluntarily can be used against you, so take advice before responding to wide information requests.

What HMRC Can Request

During an enquiry, HMRC can ask for your accounting records, bank statements, invoices, receipts, and any other documents relevant to the period under review. They can visit business premises and interview staff in some circumstances. They have formal powers to issue information notices, requiring documents within a specified timeframe, with penalties for non-compliance.

Responding to HMRC

Respond to all HMRC correspondence promptly and accurately. Do not ignore letters — HMRC will escalate if they do not receive a response. If you need more time to gather information or take professional advice, contact HMRC and ask for an extension. Be cooperative but measured — volunteer only what is requested.

Resolution

An enquiry can conclude with no changes (HMRC accepts the return as filed), an agreed settlement (you pay additional tax, interest, and potentially a penalty), or in rare cases, a formal tax assessment that can be appealed. Interest runs on underpaid tax from the original due date. Penalties depend on the nature of the error: 0% for a genuine mistake; 15–30% for careless errors; 30–70% for deliberate errors; up to 100% for deliberate and concealed errors.

Tax Investigation Insurance

Tax investigation insurance (sometimes called tax enquiry insurance) covers the professional fees of an accountant or tax adviser defending an HMRC enquiry. Many accountants offer this as part of a fee package. It is worth considering, particularly for self-employed people with complex affairs, as professional defence costs can run to thousands of pounds even for straightforward enquiries.