HMRC Compliance Enquiry After Q1 Filing: What to Expect

So HMRC Has Been in Touch After Your Q1 Filing

You filed your first MTD quarterly update, breathed a sigh of relief, and then a letter or message arrived from HMRC. Your stomach dropped. Before you panic, it helps to understand exactly what is happening, why it might have been triggered, and what you actually need to do next. This post walks you through the real process - not just "keep good records" advice, but what to expect and how to respond, step by step.

A compliance enquiry after a quarterly update is not the same as a full investigation into your tax affairs. It is usually narrower, faster, and far less alarming than it first appears. Most people who receive one resolve it without any penalty, and many without any change to what they filed.

What Is a Compliance Enquiry (and What It Is Not)

HMRC uses the term "compliance check" or "compliance enquiry" to describe a targeted look at specific figures in your filing. It is different from a formal Self Assessment enquiry, which is a much broader process with its own legal framework under Section 9A of the Taxes Management Act 1970.

A compliance enquiry after an MTD quarterly update is typically narrower in scope. HMRC might be querying one expense category, a specific income figure, or whether a particular deduction looks right. They are not, at this stage, necessarily accusing you of anything. They are asking questions.

Think of it as HMRC asking you to explain your working rather than accusing you of getting the answer wrong.

What Triggers a Compliance Enquiry After Q1

HMRC does not publish a definitive list of what flags a file for review. But based on how these enquiries work in practice, there are common patterns.

Your figures look unusual compared to previous years

If your income is significantly lower or your expenses are significantly higher than what HMRC has on record for you, their systems may flag it. A sole trader who reported £40,000 income in their last tax return but only £5,000 for Q1 might prompt a question.

Expense categories that raise questions

Certain expense types attract more scrutiny - particularly home office costs, vehicle expenses, and mixed-use items. If you have claimed a large amount under a category that is commonly misused, that can trigger a closer look. See our post on common MTD expense miscategories for the ones to watch.

Your income looks low relative to your industry

HMRC uses benchmarking data across industries. If a plumber or a landlord's figures fall well outside the typical range for their sector, it can prompt a query.

You amended your filing after submission

Amendments are not inherently suspicious, but they can draw attention - particularly if the change is significant. If you recently amended your quarterly update, HMRC may want to understand why.

Random selection

Some enquiries are genuinely random. HMRC selects a proportion of filings for review as a matter of routine, regardless of whether anything looks wrong. If yours was selected this way, there may be nothing specific they are worried about.

How HMRC Will Contact You

HMRC does not usually open a compliance enquiry with a phone call. You will typically receive one of the following:

• A letter sent to your registered address
• A message in your HMRC online account or business tax account
• Occasionally, a letter addressed to your agent if you have an accountant acting on your behalf

The letter will explain what HMRC is looking at and what they are asking you to provide. Read it carefully. It should tell you which period or figures are under review, what information they want, and the deadline for your response.

What HMRC Typically Asks for First

The initial request is usually not a demand to hand over every document you own. HMRC tends to start with a specific, focused request. Common first asks include:

• Bank statements for the quarter in question
• Invoices or receipts for a specific expense category
• Evidence that an expense was wholly or partly for business use
• An explanation of a particular income figure - for example, if one month looks very different from others
• Letting agreements or rental income records, if you are a landlord
• Mileage logs, if you have claimed vehicle costs

This first request sets the tone. If you respond promptly and provide what they ask, many enquiries resolve at this stage. If you cannot provide what they ask, or if your records do not match your filing, the enquiry is likely to widen.

Our post on what backup records to keep for your quarterly update covers exactly the kind of documents HMRC expects to see.

What to Do in the First 48 Hours

This is the most important window. What you do (or do not do) in the first two days sets up everything that follows.

Step 1: Read the letter in full before doing anything else

Do not skim it. Do not assume you know what it says. Read every line, note the specific period they mention, and identify the deadline they have given you. Write that deadline on your calendar immediately.

Step 2: Do not contact HMRC until you understand exactly what they are asking

It is tempting to ring HMRC straight away to "sort it out." Do not. Calling before you have gathered your records and understood the question often creates more problems - you may volunteer information you did not need to provide, or make statements you later have to walk back.

Step 3: Locate the records relevant to the period under review

Pull together your bank statements, invoices, receipts, and any other documents that relate to the quarter HMRC has mentioned. Keep these separate from your other records so you can find them quickly.

Step 4: Check your filed figures against those records

Open your MTD software and look at exactly what you reported. Compare those figures to your actual records. Do they match? If there is a discrepancy, you need to understand why before you respond to HMRC.

Step 5: Decide whether you need professional help

More on this below, but this decision is best made early - not after you have already sent a response you cannot take back.

How Long You Have to Respond

HMRC usually gives 30 days to respond to an initial compliance enquiry letter. This is not a hard rule and can sometimes be extended, but do not ignore the deadline. Failing to respond on time can result in information notices and, eventually, penalties.

If you need more time - for example, to gather records that take time to obtain, like bank statements from a specific period - you can contact HMRC and ask for an extension. Do this in writing, explain why you need more time, and keep a record of the request and any response.

What to Include in Your Response

Answer the specific question HMRC has asked. No more, no less. This is not the time to proactively offer up information about other quarters or other matters they have not mentioned.

Your response should:

1. Be in writing (even if HMRC contacts you by phone, follow up in writing)
2. Reference the case reference number from their letter
3. Directly address the specific figures or categories they mentioned
4. Include copies of the supporting documents they requested (keep the originals)
5. Explain anything that might look unusual - if your expenses were high in Q1 because you bought equipment in April, say so and provide the invoice

Keep a copy of everything you send. If you post documents, consider using Royal Mail Signed For so there is proof of delivery.

Common Scenarios and What Usually Happens

Scenario 1: You claimed an expense and you have the receipt

This is the simplest outcome. You send the receipt, HMRC confirms it satisfies their query, and the enquiry closes. No penalty, no adjustment, no further action.

Scenario 2: You claimed an expense but cannot find the receipt

This is trickier. HMRC may accept a bank statement showing the payment as supporting evidence, particularly for smaller amounts. For larger amounts, a missing receipt is a problem. You may need to repay any tax benefit from that deduction.

Our post on how long to keep MTD records explains why you should hold on to your documents for at least five years from the filing deadline.

Scenario 3: You realise you made a mistake

If, while reviewing your records, you spot that you over-claimed or under-reported income, do not wait for HMRC to find it. Voluntary disclosure almost always results in lower penalties than HMRC discovering the error themselves. Depending on the timing, you may be able to amend your quarterly update.

Scenario 4: The expense is legitimate but unusual

If you claimed something that looks odd but is genuinely allowable, the key is explanation. Write a short, clear note explaining what the cost was, why it was for business, and what the business benefit was. Attach the receipt. HMRC enquiry officers respond to clear, honest explanations with documentation.

When to Bring in an Accountant

You do not automatically need an accountant to handle a compliance enquiry. Many are straightforward enough to manage yourself, particularly if your records are in good order and the query is about a single, well-documented item.

However, bring in a tax professional if:

• The letter mentions potential penalties or refers to an investigation under Code of Practice 9 (this indicates HMRC suspects fraud)
• HMRC is asking about multiple quarters or multiple income sources, not just Q1
• You know your records are incomplete or inconsistent with what you filed
• You are not confident you understand what HMRC is asking
• The amounts involved are significant enough that a mistake in your response could be costly
• HMRC has asked to visit your premises or speak to you in person

If you do decide to use an accountant or tax agent, appoint them quickly - before you have sent any response. They need to be authorised to act on your behalf via HMRC's agent authorisation process, which takes a little time to set up. It is much easier for an agent to take over before anything has been said than to unpick a response that has already gone in.

What Happens Once the Enquiry Closes

When HMRC is satisfied, they will issue a closure notice. This confirms that the enquiry is complete and, if applicable, states any adjustment to your figures. If the enquiry found nothing wrong, the closure notice simply confirms that no changes are needed.

Once closed, the same period cannot normally be reopened unless HMRC discovers evidence of fraud or deliberate concealment. An ordinary compliance enquiry that closes without findings gives you a clean slate for that quarter.

After the enquiry, it is worth reviewing your record-keeping process. Not because you did anything wrong, but because a well-organised system makes future enquiries - if they ever arise - much easier to handle. Our guide to HMRC record-keeping standards for MTD covers what "good" looks like in practice.

How to Protect Yourself Going Forward

The best defence against a difficult compliance enquiry is simply keeping accurate, organised records throughout the year. That means:

• Saving receipts at the time of purchase, not hunting for them months later
• Reconciling your bank statements to your income and expense records each quarter
• Being consistent in how you categorise expenses - see our post on expense miscategories to avoid
• Not over-claiming on mixed-use items like your phone or home office - our guide on claiming the business percentage explains how to do this properly
• Keeping your records for at least five years after the relevant filing deadline

If you are a landlord with rental income, our posts on responding to HMRC rental income queries and repairs versus capital works cover the areas that tend to attract landlord-specific scrutiny.

The Bottom Line

A compliance enquiry after your Q1 filing is not the disaster it might feel like when the letter arrives. In most cases, it is a specific, time-limited process that resolves cleanly if you have kept your records, respond honestly, and answer only what is asked. Read the letter carefully, gather your documents, give yourself the full response window, and get professional help if the scope or seriousness of the enquiry goes beyond a straightforward query. The vast majority of sole traders and landlords who receive these letters close them without any penalty and without any change to what they filed.