Receiving a letter from HMRC to say your tax affairs are under review is one of the more unsettling things that can land on a business owner’s desk. The immediate assumption is that something has gone wrong — but that isn’t always the case. Some investigations are triggered by specific data discrepancies, others by industry risk factors, and a small proportion are entirely random. What matters is understanding what draws HMRC’s attention in the first place, and being in a position to respond clearly and calmly if it happens to you. As a chartered accountant Essex businesses trust for compliance and tax support, this is a conversation we have with clients more often than you might expect.
How HMRC Decides Who to Look At
HMRC doesn’t rely on gut feel. It uses a sophisticated data system called Connect, which cross-references information from banks, Companies House, PAYE records, Land Registry, online selling platforms, and other sources against what you’ve declared on your tax returns. When the numbers don’t match — even innocently — the system flags it for review. With Making Tax Digital now live for self-employed individuals and landlords earning above £50,000, HMRC is also receiving quarterly transaction-level data directly from accounting software, meaning any inconsistency between quarterly updates and annual returns is picked up automatically.
The Most Common Triggers
Certain patterns are more likely than others to attract attention. Unusually high expense claims relative to your income or sector averages are one of the most consistent red flags — HMRC uses industry benchmarks, so if your margins look significantly out of step with similar businesses, it will notice. Sharp, unexplained swings in declared income between tax years are another signal, as are persistently late or amended returns, which suggest to HMRC that record-keeping may not be as robust as it should be.
Cash-intensive businesses have historically attracted more scrutiny, simply because income is harder to verify independently. Similarly, rental income, online marketplace earnings, and cryptocurrency are all areas where third-party data is now shared directly with HMRC — leaving any of these off a return is one of the most common reasons a straightforward year turns into a compliance check. For construction businesses specifically, errors in CIS returns or unregistered subcontractors frequently trigger enquiries, which is why getting CIS right from the outset matters far more than most people realise. If you’re in the construction or recruitment sector and want a second opinion on your compliance position, our financial advisor Essex team is well placed to help.
Being Investigated Doesn’t Mean You’ve Done Something Wrong
This is worth saying plainly. Many checks are resolved without any change to the tax due, particularly where a business has kept accurate records and filed its returns honestly. Being selected doesn’t mean HMRC suspects fraud — it means something in your data caught the system’s attention, and HMRC wants to understand it. The businesses that tend to come through investigations most smoothly are those with clean records, consistent returns, and an accountant who can respond promptly and clearly on their behalf.
What HMRC Can Actually Do
An investigation can cover a single tax year or, in cases where HMRC suspects deliberate errors, potentially go back much further. It can focus on one area — VAT, payroll, or corporation tax — or look at the business’s position more broadly. HMRC has the right to request records, ask detailed questions, and visit business premises. You also have rights throughout this process, including the right to appeal HMRC’s conclusions and, if necessary, take the matter to the independent First-tier Tribunal. Understanding those rights is part of what about us and what good accountancy support is for — you shouldn’t be navigating this alone.
How to Reduce Your Risk
The most effective protection against an investigation is simply good practice maintained consistently. Keeping accurate, up-to-date records, filing returns on time, declaring all sources of income, and making sure your expenses are genuinely allowable and properly documented all significantly reduce the likelihood of HMRC flagging your return. Where your figures look unusual for a legitimate reason — a difficult year, a one-off asset purchase, a change in business structure — making sure that’s documented clearly is far better than leaving it unexplained.
If HMRC Does Make Contact
The single most important step if you receive an HMRC enquiry letter is not to respond without taking professional advice first. What you say in early correspondence can shape how the investigation develops, and it’s far easier to manage the process correctly from the start than to correct an unhelpful early response later. Contact us as soon as the letter arrives — we can review what HMRC is asking, advise on the appropriate response, and represent your business through the process if needed.