Received HMRC Letter? Here's What To Do in the UK

Getting a letter from HMRC can send a chill down your spine. But receiving an HMRC letter doesn't automatically mean you're in trouble—and it definitely doesn't mean you should ignore it. What you do next matters enormously. In this guide, we'll walk you through exactly what to do when you received HMRC letter notifications, how to understand what they want, and the most effective steps to take to protect yourself.

Common Reasons You've Received an HMRC Letter

HMRC sends millions of letters each year. Most aren't accusations—they're requests for information, confirmations, or notifications about your tax account. Understanding which category your letter falls into is your first priority.

• Self-assessment queries: They've spotted a discrepancy or inconsistency in your return and want clarification
• Payment reminders: You owe tax that's now due or overdue
• Late payment penalties: Interest and penalties have been assessed on unpaid taxes
• Compliance notices: They want you to file a return or provide evidence you're not trading
• VAT or PAYE issues: Problems with your VAT return or employee tax deductions
• Tax investigation: They're conducting an inquiry into your tax affairs (rare for most people)

The letter itself will tell you which category applies. Read it carefully—twice. Don't let fear cloud your judgment.

Step One: Understand What HMRC Actually Wants

When you received an HMRC letter, the first thing is to identify what action it requires:

• Is there a specific question they want answered?
• Is there a deadline for response?
• Are they asking for payment?
• Are they asking for documents or evidence?
• Is this a courtesy notice, or a formal demand?

HMRC letters always contain a reference number and usually a response deadline (typically 30 days, sometimes 60). This deadline is not negotiable on minor queries, though you can request extensions if you have genuine reasons.

Check the letter carefully for:

• The type of letter (CT600, SA notice, assessment notice, etc.)
• What tax year(s) it relates to
• The exact amount in question, if any
• Contact details for the HMRC officer dealing with it
• The deadline for response

Step Two: Gather Your Records Immediately

The moment you received an HMRC letter, start collecting your paperwork. Do this before you respond to anything. You'll need:

• Business bank statements from the relevant tax year
• Invoices (both issued and received)
• Expense receipts (categorized by type: premises, travel, equipment, etc.)
• Payroll records if you have employees
• VAT records if VAT registered
• Previous years' tax returns and assessments

If your records are patchy, now is the time to reconstruct them as honestly as you can. Most small business owners don't keep perfect records, and HMRC knows this. They're usually interested in reasonableness, not perfection.

Step Three: Determine if You Need Professional Help

This is the most important decision. Some letters you can handle yourself. Others require an accountant or tax specialist.

Handle it yourself if:

• It's a simple admin issue (address confirmation, basic self-assessment clarification)
• You have clear records to support what you filed
• The amount in question is small (under £500)
• You understand the specific query

Get professional help if:

• It's a formal investigation or enquiry notice
• The amount in question is substantial
• You don't understand what they're asking
• Your records are incomplete
• It involves VAT, PAYE, or corporation tax (not self-assessment)
• They're asking about multiple years

Paying for a good accountant or tax advisor at this point is money well spent. They know how HMRC works, what arguments carry weight, and how to structure your response to minimize your exposure.

Responding to HMRC: The Core Rules

Whether you're handling this yourself or with professional help, follow these principles:

• Meet the deadline. Missing it can result in penalties. If you can't meet it, contact HMRC and ask for an extension before the deadline passes.
• Be honest. You cannot lie to HMRC. You can explain, contextualize, and present your strongest case—but you cannot fabricate.
• Be complete. If they ask for documents, provide everything relevant, not just the bits that look good.
• Keep it professional. Emotional responses, accusations, or rambling explanations don't help. Stick to facts and figures.
• Get written confirmation. If you speak to HMRC by phone, follow it up in writing with a summary of what was discussed and agreed.

Payment Issues and Late Payment Interest

If your HMRC letter relates to unpaid tax, understand how interest accrues. This is where knowing the rules can save you money.

Under the Late Payment of Commercial Debts (Interest) Act 1998, when you owe taxes to HMRC, interest accumulates daily. As of April 2026, the statutory rate is 8% plus the Bank of England base rate, currently standing at 4.50%, making a total statutory rate of 12.50% per annum.

This means:

• A £10,000 tax bill overdue for 90 days could accrue over £310 in statutory interest alone
• The longer you wait, the worse it gets (this compounds)
• HMRC will also add penalties on top (typically 5% of the unpaid tax if paid within 12 months, rising to 10% after)

If you owe tax and have received a letter about it, your priority is to pay it as quickly as possible, even if you dispute part of the amount. You can pay the disputed portion separately and appeal on that specific issue while the agreed amount is settled.

Common HMRC Letter Scenarios and How to Respond

Self-Assessment Discrepancy Query

They've noticed something unusual in your return (income doesn't match your sources, expenses seem high, etc.). Respond by providing clear documentation. If you genuinely made a mistake, offer to amend your return. Most of these are resolved quickly.

Request for Documents

They want to see your invoices, receipts, or bank statements. Provide them, organized and clearly labeled. If you're missing some documents, explain what happened and provide what you do have. Don't panic—missing receipts for old expenses don't automatically disallow them.

Penalty Notice

You failed to file on time or pay on time, and they're charging a penalty. Check if you have a reasonable excuse (illness, bereavement, system failure). If you do, appeal. If not, pay it—arguing when you clearly missed a deadline won't help.

Payment Demand with Interest

This is urgent. Pay what you can immediately, even if you dispute part of it. Contact HMRC to discuss a payment plan if you can't pay in full. The statutory interest at 12.50% is relentless.

Compliance Notice (You're Not Responding)

If you've been ignoring letters, this is serious. Respond immediately, even if just to acknowledge receipt and explain why you haven't responded yet. Persistent non-response leads to civil penalties.

Your Rights When You Received an HMRC Letter

HMRC has significant powers, but you have rights too:

• The right to understand: If the letter is unclear, ask for clarification before responding
• The right to be represented: You can have a tax advisor, accountant, or solicitor represent you
• The right to appeal: If you disagree with HMRC's decision, you have a formal appeals process
• The right to ask for reasonable excuse consideration: If you missed a deadline, you can ask them to consider whether you had a reasonable excuse
• The right to complain: If HMRC treats you unfairly, you can escalate to the Taxpayer's Ombudsman

Don't assume you're powerless. If HMRC has made an error or acted unreasonably, pushing back is legitimate.

Timeline: What Happens Next

Understanding the typical process helps you know what to expect:

• Days 1-3: You read the letter carefully and gather documents
• Days 4-7: You respond (ideally with professional help if appropriate)
• Weeks 2-4: HMRC reviews your response. Simple issues resolve here
• Weeks 4-8: More complex matters may see follow-up questions from HMRC
• Weeks 8+: If significant money or principle is at stake, this could go to formal dispute

Throughout this process, you're entitled to be treated fairly and to understand what's happening. Ask questions. Request updates if it's gone quiet for over a month.

Prevention: Making Sure You Don't Get Another Letter

Once you've dealt with this letter, prevent future ones:

• Keep better records. Use accounting software. Photograph receipts. Categorize expenses consistently.
• File on time. HMRC penalizes late filing heavily. Use your accountant's reminders if you struggle with deadlines.
• Respond to HMRC promptly. Even if you don't have everything they ask for, acknowledge receipt and say when you'll respond.
• Pay on time. The 12.50% statutory interest is brutal. Set reminders for tax deadlines months in advance.
• Be transparent. If something looks unusual in your accounts, explain it proactively in your return notes.

Final Thoughts: Don't Panic, Take Action

Receiving an HMRC letter is stressful, but it's manageable. The key is to act quickly, understand what they want, be honest, and seek professional help if the issue is complex. Most HMRC inquiries resolve without major drama—they're usually about clarification, not accusation.

The worst thing you can do is ignore the letter. The second-worst is panic and do something foolish. The best thing is to read it carefully, gather your records, take a breath, and respond properly.