Tax Investigations: What Triggers HMRC Enquiries in 2025 and How to Prepare
Why Tax Enquiries Are on the Rise Again
In 2025, HMRC has significantly ramped up its compliance activity, increasing both the number and intensity of tax enquiries. Following years of backlogs and leniency post-pandemic, the current climate is clear: expect more scrutiny, fewer extensions, and quicker intervention.
For individuals and businesses, the consequences of an HMRC enquiry can range from time-consuming admin to serious financial penalties. With automated risk analysis, cross-checking across government databases, and increasing use of AI, many enquiries are now triggered without human oversight.
If you’re a business owner, landlord, company director or self-employed individual, understanding what prompts a tax enquiry in 2025 is essential. But more important still is preparing a clear, defendable position — before HMRC comes knocking.
What Is a Tax Enquiry?
A tax enquiry (or investigation) is HMRC’s formal review of a taxpayer’s returns, records or disclosures. It can be:
- Aspect enquiry: Focused on a single item (e.g. expenses, dividends, property income)
- Full enquiry: A full review of your entire return or business affairs
- Discovery assessment: Triggered by new information or perceived fraud
- Unannounced visit: Usually reserved for suspected serious evasion
Enquiries can relate to income tax, corporation tax, VAT, PAYE, CGT, or even SDLT. They may cover one tax year or span several.
Common Triggers for HMRC Enquiries in 2025
HMRC doesn’t reveal its risk scoring algorithms — but certain patterns and inconsistencies will raise red flags. Common 2025 triggers include:
1. Large or Unexplained Variations
Year-on-year changes in income, expenses or margins
Decline in declared profits despite consistent turnover
Sudden spike in pension contributions or dividend payments
2. Mismatched Data from Third Parties
- Discrepancies between tax returns and bank interest, dividend or property income reported by institutions
- Differences between your VAT returns and supplier/customer declarations
- PAYE inconsistencies between FPS submissions and actual payments
3. Property Income and Capital Gains
- Missing or underreported rental income (especially where properties are listed online)
- Unexplained sales of property or land not included in self-assessment
- Non-disclosure of capital gains following disposal of crypto, shares or assets
4. High-Risk Professions and Business Models
- Cash-heavy businesses (e.g. hospitality, construction, retail)
- Freelancers with high expenses relative to income
- Property developers with inconsistent profit declarations
5. Company Director Activity
- Low salary but high lifestyle indicators (cars, travel, property)
- Multiple shareholder dividends with no evidence of retained profits
- Excessive director loan accounts with little or no repayment
6. Use of Avoidance Schemes
Employer Benefit Trusts (EBTs)
Offshore income without declaration
Scheme Reference Numbers (SRNs) in the return
How Are Investigations Initiated?
Most HMRC enquiries begin in one of three ways:
- Automatic selection: Software flags anomalies or risks
- Manual selection: HMRC officers investigate patterns or tips
- Random selection: Occasionally used to deter under-reporting
Many businesses are now flagged by HMRC’s Connect system, which analyses over a billion pieces of data from:
- Banks and financial institutions
- Companies House
- DVLA
- Land Registry
- Airbnb, Booking.com and other rental platforms
- Social media and web presence
In 2025, with Connect becoming more accurate, even small mistakes can trigger formal contact.
What to Expect During an Enquiry
An HMRC enquiry typically begins with a formal letter requesting records. This may include:
- Full business accounts
- Bank statements
- Invoices, receipts and ledgers
- Contracts or agreements
- Explanations for large payments or discrepancies
You are normally given 30 days to respond. If not dealt with properly, it can escalate quickly into formal investigation or lead to:
- Penalties of up to 100% of the unpaid tax
- Interest on late payments
- Assessments going back up to 20 years
- Loss of repayment claims or allowances
Defending Against an Enquiry: Best Practices
Whether you’re under investigation or want to reduce your risk, these steps are essential:
1. Keep Proper Records
Maintain complete records for six years including:
- Sales invoices, receipts and bank records
- Mileage logs and expenses
- Proof of income sources and work undertaken
- Property ownership and rental agreements
2. File Accurate Returns On Time
- Avoid estimates and late submissions
- Match accounting figures with banking records
- Use HMRC-recognised software and agents
3. Declare All Income
- Include freelance work, crypto gains, online sales, dividends, and foreign income
- Report all property income — even from occasional lets
4. Work with a Qualified Accountant
An experienced accountant can:
- Spot errors before submission
- Ensure correct reliefs are applied
- Defend you during a formal enquiry
- Act as your representative in correspondence with HMRC
Merranti has represented clients through hundreds of HMRC enquiries — with outcomes ranging from full clearance to major penalty reductions.
5. Consider Fee Protection Insurance
Tax investigation insurance covers the professional fees incurred when defending an enquiry — which can often exceed £3,000 to £10,000 for complex cases.
We recommend all Merranti clients consider this cover as standard.
Key Tax Investigation Risks in 2025
HMRC investigations have increased significantly in 2025, driven by AI-powered detection systems. Triggers include unexplained income changes, property sales, large expenses, and undeclared freelance or online income. Data matching from banks, Land Registry and rental platforms increases the likelihood of detection. Business owners should maintain full records, file accurate returns, and work with qualified accountants to minimise risk and protect their position during an enquiry.
How Merranti Accounting Can Help
Whether you’re facing a current enquiry or want to proactively defend your business, Merranti provides practical, expert support including:
- Self-assessment and company tax return reviews
- Enquiry representation and correspondence management
- Property income and CGT reporting
- Director tax planning and loan account reviews
- VAT and PAYE audit support
- Tax investigation insurance options
Don’t wait for HMRC to contact you. If you suspect an issue or want peace of mind, our tax team can help you prepare, respond, or resolve the matter efficiently.
Call: 01342 836 557
Email: contactus@merranti.com
