A letter or email from HMRC can unsettle even a well-run business. Knowing the top warning signs of an HMRC enquiry helps you deal with potential issues early, keep the right evidence and respond calmly if questions arise. An enquiry does not automatically mean HMRC believes you have done something wrong. It may be a routine check, a targeted review or a request for clarification. The difference often lies in how prepared your records are.
For owner-managed businesses, sole traders, landlords and higher-income taxpayers, the best protection is not last-minute paperwork. It is accurate bookkeeping, sensible tax planning and regular review throughout the year.
What is an HMRC enquiry?
An HMRC enquiry is a formal examination of a tax return or other tax submission. It can relate to Self Assessment, corporation tax, VAT, PAYE or another area of tax compliance. HMRC may ask for records, explanations, calculations and supporting documents before deciding whether the return is correct.
Some enquiries are selected at random. Others are prompted by information HMRC already holds, patterns in a return, third-party data or figures that appear inconsistent with previous years. A query can be narrow and focused on one point, or wider where HMRC believes more of the return needs checking.
The practical point is simple: do not ignore correspondence or assume a quick informal reply will always be enough. Deadlines matter, and an incomplete response can turn a manageable question into a longer, more expensive process.
Top warning signs of an HMRC enquiry
There is no public checklist that confirms an enquiry is coming. HMRC uses a range of data and risk assessments, and even perfectly compliant taxpayers can be selected. However, the following situations are common reasons for questions and deserve closer attention.
Figures that do not match the wider picture
A sudden fall in profit, a sharp increase in expenses or a major change in turnover is not a problem by itself. Businesses change direction, lose customers, invest in equipment and face rising costs. But where the figures differ markedly from earlier returns or typical results in the sector, HMRC may want an explanation.
For example, a café reporting stable card sales but substantially lower VATable takings needs a clear record of why. A consultant claiming high travel costs while working mainly from home should be able to show that the journeys were wholly and exclusively for the business. The issue is not whether a figure looks unusual. It is whether the figure can be evidenced.
Income missing from a return
HMRC receives information from many sources, including employers, banks, property agents, online platforms, Companies House and other government systems. Income that is omitted, reported late or does not align with this information can prompt a query.
This particularly affects directors who receive salary, dividends, benefits or loans from their company, as well as landlords with rental income and self-employed individuals taking payments through several channels. Cash sales and informal payment arrangements require just as much care as card or bank transactions. If money has come into the business, there should be a clear accounting trail for it.
Expense claims that are personal, rounded or poorly supported
Expenses are a regular area of enquiry because the rules can be misunderstood. A cost must have a genuine business purpose, and the business element should be claimed where an expense has mixed personal and commercial use.
Repeated round-sum claims, large entertainment costs, unclear motor expenses and frequent payments to a director without supporting records can all raise questions. This does not mean a legitimate claim should be avoided. It means receipts, mileage logs, invoices and a short explanation should be retained while the details are fresh.
For limited companies, it is also sensible to review the director’s loan account regularly. An overdrawn or unexplained balance can create tax consequences and can be harder to resolve once the year-end has passed.
VAT returns that do not agree with accounts or sales records
VAT is data-heavy and time-sensitive, making it a frequent focus for checks. Common warning signs include late VAT returns, repeated repayment claims, unusually low output VAT, changes in the VAT liability of sales, or differences between VAT returns and annual accounts.
Errors are often caused by process rather than intent. A business may use the wrong VAT code, miss sales invoices, reclaim input VAT without valid evidence, or fail to account correctly for deposits and credit notes. The right treatment depends on the transaction, so guessing is rarely a good commercial decision.
Regular bookkeeping and reconciliation of sales, purchases, bank transactions and VAT control accounts make discrepancies easier to spot before a return is filed. This is also increasingly relevant as Making Tax Digital places greater emphasis on digital records and a reliable VAT return process.
Losses, low profits or lifestyle inconsistencies
Making a loss is not evidence of wrongdoing. New businesses can take time to become profitable, and established businesses can experience difficult trading periods. However, repeated losses alongside significant personal spending, asset purchases or lifestyle indicators that appear inconsistent with declared income may lead HMRC to ask how those costs were funded.
The same applies where a business consistently reports very low profits while turnover, staffing or visible activity suggests a different scale of operation. A clear explanation may be available, such as loans, savings, one-off investments or a temporary downturn. Good records allow that explanation to be made quickly and credibly.
Late filing, amendments and inconsistent record keeping
One late return will not necessarily trigger an enquiry, but persistent late filing, frequent amendments and recurring errors can make HMRC look more closely. Repeated corrections may suggest that the underlying records are not being kept properly.
This is where a year-round relationship with an accountant can make a practical difference. Waiting until the filing deadline to reconstruct a year of transactions creates pressure and increases the chance of omissions. Monthly or quarterly review gives business owners clearer information for decisions as well as better tax compliance.
Transactions between connected parties
Payments between a business, its directors, family members or related companies are legitimate in many circumstances, but they should be documented and priced appropriately. Examples include loans, rent, management charges, wages, dividends and the transfer of assets.
HMRC may ask whether a payment was genuinely for the stated purpose, whether it was authorised and whether the tax treatment is correct. Keep agreements, board minutes where appropriate, invoices and evidence of payment. Informal arrangements can be commercially sensible at the time, but they are difficult to explain years later without paperwork.
What to do if HMRC contacts you
Start by checking exactly what HMRC is asking for, which period is under review and the response deadline. Keep copies of all correspondence and do not alter or discard records. Gather the requested information methodically, including bank statements, invoices, bookkeeping reports, contracts and calculations where relevant.
It is usually better to provide a clear, accurate response than to send a large volume of unorganised documents. If something was reported incorrectly, taking advice early can help you understand the position and make a considered disclosure. Trying to explain an issue away without checking the facts can create further complications.
Do not overlook the scope of the enquiry. A full enquiry can allow HMRC to examine the whole return, while an aspect enquiry is limited to specific points. HMRC may also ask questions beyond the initial issue if the evidence suggests a wider concern. The approach should therefore be proportionate, but thorough.
Build records that stand up to questions
Good records are not simply a compliance requirement. They give you a clearer view of cashflow, margins, tax liabilities and the financial health of the business. Keep business and personal spending separate, reconcile bank accounts regularly and retain invoices and receipts in an organised digital system.
For directors, make time to review salary, dividends, expenses and loan account movements before the year-end rather than after it. For sole traders and landlords, keep income and property costs up to date throughout the year. A small amount of routine discipline is far easier than rebuilding evidence when HMRC is already asking questions.
If correspondence arrives, a calm and organised response gives you the strongest starting point. The most useful next step is to review the facts early, ask for professional support where needed and use the experience to improve the financial systems that support your business growth.