Here are five of the most common red flags that can trigger HMRC scrutiny and how to avoid them.

1. Inconsistent or Fluctuating Income: One of the first things HMRC looks for is inconsistency. If your reported income fluctuates sharply from year to year without a clear explanation, it can raise questions. For example, a sudden drop in revenue followed by a sharp increase may suggest underreporting or timing issues. Similarly, income figures that do not align with industry norms can trigger further review. Consistency matters and when changes occur, they should be supported by clear explanations such as business expansion, reduced trading periods, or one-off events. Accurate bookkeeping and proper documentation help ensure that income figures tell a coherent story.
2. High Expenses Compared to Turnover: Claiming expenses is completely legitimate. However, when expenses appear unusually high relative to income, HMRC may take a closer look. This often happens when personal costs are mixed with business expenses or when expense categories are not properly justified. Repeated claims for meals, travel, or home office costs without supporting records can be problematic. HMRC expects expenses to be wholly and exclusively for business purposes. Clear categorisation, proper receipts, and professional review help ensure that claims are accurate and defensible.
3. Repeated Late Filings or Amendments: Late submissions attract attention. So do frequent amendments to previously filed returns. While occasional mistakes happen, repeated corrections can suggest disorganisation or uncertainty in financial records. HMRC may interpret this as a sign that the underlying bookkeeping processes are weak. Submitting accurate returns on time reduces risk significantly. Strong systems and professional oversight ensure that figures are correct before submission, limiting the need for later changes.
4. VAT Irregularities: VAT is one of the most common areas for HMRC enquiries. Inconsistencies between VAT returns and annual accounts, unusually high VAT reclaims, or repeated errors can all act as triggers. Incorrect VAT treatment, especially in complex areas such as zero-rated or exempt supplies, often results from poor record keeping rather than intent. Unfortunately, HMRC focuses on accuracy, not intention. Regular reconciliation, correct VAT categorisation, and professional review reduce the likelihood of discrepancies that invite scrutiny.
5. Lifestyle Not Matching Declared Income: HMRC has access to more data than many people realise. When declared income appears low but personal spending or assets suggest otherwise, questions may follow. This does not mean business owners cannot live comfortably. It means that income reporting must align realistically with lifestyle indicators. Undeclared income, director loan misunderstandings, or informal withdrawals can create mismatches that raise concerns. Clear separation between personal and business finances and accurate reporting of drawings and salaries help maintain transparency.