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If you run a business in the UK, an HMRC enquiry probably sits somewhere on your list of quiet worries. Here’s the uncomfortable truth: that worry is more justified in 2026 than it’s ever been. HMRC has just set out an ambitious modernisation programme that puts more data, more AI, and more compliance officers behind every tax return you file — and the businesses that aren’t prepared are going to feel the difference first.
The good news is that none of this needs to be frightening if you act now. Here’s what’s actually changing, what triggers a check, and how to make sure your business is ready before, not after, HMRC comes knocking.
What Is an HMRC Enquiry, Really?
An HMRC enquiry (officially a “compliance check”) is a formal review of your tax returns, accounting records and business affairs, carried out under Schedule 36 of the Finance Act 2008. It can cover Corporation Tax, VAT, PAYE, Self Assessment, or a single specific transaction such as a property sale or an R&D claim.
An enquiry doesn’t automatically mean HMRC thinks you’ve done something wrong. Checks can end with more tax owed, less tax owed, or no change at all. But you’ll only get that favourable outcome if your records can back up what you’ve declared — and HMRC now has far more ways of checking that than it used to.
HMRC’s Digital Modernisation Plans: Why This Matters Right Now
In July 2026, HMRC published an update to its five-year Transformation Roadmap, alongside a separate “Tax Update 2026” package of reforms. Together, they mark the biggest shift in how HMRC administers, and polices, the tax system in a generation. For small business owners, three changes stand out:
- 5,500 new compliance officers. HMRC is actively recruiting and training thousands of additional compliance and debt management staff, alongside a growing programme of AI tools designed to flag anomalies and support caseworkers. More people, working faster, checking more returns.
- Reformed information and inspection powers. The government is updating Schedule 36 of the Finance Act 2008 — the law behind HMRC’s information notices — specifically so HMRC “can effectively access and process information in a modern, digital economy.” In plain English: HMRC’s legal power to request your digital records is being widened and modernised, not narrowed.
- Greater use of third-party data. HMRC is expanding its use of external data to pre-populate tax returns and check PAYE tax codes, building on systems that already cross-reference bank data, payroll submissions, and income reported by online marketplaces. The more data sources HMRC plugs in, the harder it becomes for inconsistencies in your figures to go unnoticed.
On top of this, HMRC is moving to a “digital by default” model for outbound communications and mandating registration for tax advisers from April 2026 — part of a wider effort to clean up who and what sits between taxpayers and HMRC. The direction is unmistakable: less paper, more automation, and considerably more visibility into every business’s affairs.
None of this is going away. HMRC has been explicit that this is a multi-year programme running through to 2027 and beyond. Businesses that treat 2026 as “business as usual” are the ones most likely to be caught out.
What Triggers an Enquiry?
Only a small proportion of HMRC checks are genuinely random — roughly one in fifteen. The overwhelming majority are triggered by something specific, and HMRC’s modernisation plans are making these triggers easier than ever to spot automatically. Common red flags include:
- Inconsistencies across returns — figures on your VAT return that don’t match your Corporation Tax or PAYE filings
- Unusual patterns or sudden changes — rapid growth, a big drop in turnover, or margins that look out of step with your sector
- Lifestyle mismatches — spending (property, cars, school fees) that doesn’t add up against declared income, particularly for owner-managed businesses
- Data-matching from third parties — HMRC’s Connect system cross-references bank data, payroll (RTI) submissions, and income reported by online marketplaces such as eBay, Vinted, Airbnb and Etsy, with these feeds only set to expand
- Not being on Making Tax Digital — from April 2026, sole traders and landlords with qualifying income over £50,000 must comply with MTD for Income Tax. HMRC has confirmed that failing to sign up is now treated as a high-priority risk indicator in its own right
- Sector or SIC-code targeting — HMRC periodically focuses compliance resource on particular industries or claim types, R&D tax relief being a well-known recent example
- No recent history of review — VAT-registered businesses that haven’t had any HMRC scrutiny in five years are currently being sent “nudge letters” warning that around half of recipients will go on to face a check
What Happens Once a Check Opens
HMRC will normally write to you first, setting out which tax and period is under review and what information it wants. A check can start narrowly — one quarter’s VAT return, say — but it can extend to earlier years or other taxes if something in your records raises further questions. The statutory window for going back varies with the type of error involved: broadly four years for careless mistakes, six years for deliberate errors, and up to twenty years where deliberate concealment is found.
If HMRC formally requests documents under a Schedule 36 notice, you generally have to comply or appeal within 30 days; ignoring a valid notice can bring its own penalties. Where an error is confirmed, you can expect an assessment for the extra tax, interest backdated to when it was originally due, and a penalty scaled to how the error is classified — careless, deliberate, or deliberate with concealment. With HMRC actively consulting on modernising and toughening its penalty framework, the cost of getting caught out is only going one direction.
How to Reduce Your Risk (and Your Stress)
You can’t make your business “enquiry-proof” — even well-run, diligent businesses get selected. But in a world where HMRC has more data, more staff and more automation working against every return you file, being prepared has stopped being optional. Here’s how to stay ahead:
- Keep clean, contemporaneous records. Reconcile VAT, PAYE and Corporation Tax data regularly rather than at year-end — the same data now sitting in HMRC’s systems in near real time.
- Document your reasoning, not just your numbers — notes on judgement calls, valuations or reliefs claimed are gold if HMRC ever asks “why?”
- Get ahead of Making Tax Digital. If it applies to you, sign up in good time rather than waiting to be flagged as non-compliant.
- Review before HMRC does. A proactive VAT or PAYE health check can catch and correct issues on your own terms, often with a much smaller penalty than if HMRC finds them first.
- Don’t go it alone if a letter arrives. Correspondence handled through a regulated, registered adviser tends to move faster and more smoothly than direct director-to-HMRC contact — and from April 2026, adviser registration itself becomes mandatory.
The Bottom Line
HMRC enquiries are becoming more frequent, more data-driven and increasingly difficult to predict. HMRC’s own modernisation plans make it clear that this is a long-term shift, not a temporary compliance campaign. The businesses that come through a compliance check with the least disruption are rarely those that never make mistakes—they’re the ones with accurate records, robust bookkeeping and professional support when it matters most.
While no one can prevent an HMRC enquiry altogether, you can reduce both the risk and the financial impact. Tax Investigation Insurance helps cover the professional fees involved in responding to many types of HMRC compliance checks and enquiries, giving you access to expert support without worrying about unexpected accountancy costs at what can already be a stressful time.
If you’d like to strengthen your records, find out whether Tax Investigation Insurance is right for your business, or simply have the reassurance of experienced professionals on your side, our team is here to help. As ICAEW Chartered Accountants, we provide practical, proactive tax advice and support businesses throughout every stage of an HMRC enquiry—helping you stay compliant, protected and focused on running your business with confidence.
This article is for general guidance only and does not constitute tax advice. Every business’s position is different — please contact us to discuss your specific circumstances.