An HMRC tax investigation may take place if/when HMRC suspects incorrect information has appeared in a tax return.
HMRC investigations, sometimes referred to as “Tax Compliance Checks,” can understandably cause significant stress for anyone involved. These reviews are becoming increasingly common as HMRC seeks to ensure that both individuals and businesses are paying the correct amount of tax.
Any person or organisation that submits a UK tax return can be selected for investigation. HMRC’s inspectors will review financial records to identify any discrepancies or signs of irregular activity. Their highly effective “Connect” system is constantly analysing large volumes of financial data, enabling HMRC to highlight cases for further scrutiny.
This guide explains what businesses can expect during an HMRC investigation.
What may trigger the HMRC investigation
There are several reasons HMRC may open an investigation. Many relate to information submitted in your tax returns, but external factors can also play a role. Common triggers include:
- A sudden or unexpected change in income or expenditure
- Discrepancies within submitted tax returns
- Business costs that appear unusually high for your industry or sector
- Tips or information received from whistle-blowers or external sources
Important: Many HMRC investigations are entirely random or linked to routine checks on higher‑risk sectors. Being selected does not necessarily mean your tax affairs are incorrect.
How will HMRC notify the business?
Before an investigation begins, HMRC will contact the business directly - either in writing or by telephone. This initial communication will outline the areas HMRC intends to review and whether the enquiry relates to specific concerns or your tax affairs more broadly.
If you have an accountant, HMRC may also contact them as your authorised representative.
Which business taxes may be subject to HMRC investigation?
What Taxes Can HMRC Investigate?
HMRC has wide statutory powers and can investigate almost any UK tax, for both individuals and businesses. The types of tax most commonly examined are:
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Income Tax - HMRC regularly reviews Self‑Assessment returns, employment income, rental income, dividends, crypto gains, and undeclared earnings.
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Corporation Tax - Companies can face checks into their CT600 returns, accounts, transfer pricing, director loan accounts, and allowable expenses.
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VAT - VAT investigations include repayment claims, discrepancies between accounts and VAT returns, and sector‑specific risk reviews.
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Capital Gains Tax (CGT) - HMRC investigates property disposals, share sales, cryptoasset disposals, and missing gains in Self‑Assessment.
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PAYE & Employment‑Related Taxes - Includes PAYE payroll checks, P11D benefits, National Insurance, and payroll RTI discrepancies.
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Construction Industry Scheme (CIS) - Contractor and subcontractor filings, deductions, mismatches with RTI, and false claims.
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IR35 / Off‑Payroll Working - HMRC reviews employment status, contracts, intermediaries, and fee‑payer compliance.
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National Minimum Wage - Often targeted at employers with high numbers of hourly‑paid workers or historic payroll issues.
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Stamp Duty Land Tax (SDLT) - Discrepancies in property transactions, incorrect relief claims, and undeclared purchases.
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Other Areas HMRC Commonly Reviews - HMRC’s modern data‑matching systems mean checks also occur in areas such as:
- Offshore income & foreign assets
- Cryptocurrency transactions
- Research & Development (R&D) tax credits
- Benefit‑related fraud
How an HMRC investigation works
The structure and timescales of an investigation can vary. In most cases, HMRC will request information such as financial statements, transaction details, and full business accounts.
Businesses must provide the information requested, although there is a right to appeal certain decisions.
HMRC can investigate any person or business at any time, even without suspicion, through:
- Random checks
- Aspect enquiries (focused on one issue)
- Full enquiries (full review of returns and records)
They can generally look back 4–6 years, and up to 20 years for deliberate tax evasion.
Types of HMRC Enquiries
HMRC can open several different types of enquiries depending on the level of risk, suspicion, or the issue identified in a tax return. These are the main enquiry types recognised in current HMRC practice:
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Aspect Enquiry - A targeted enquiry looking at a single issue or a small part of a tax return—e.g., expenses, dividends, rental income, VAT figures, etc.
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Full Enquiry - A comprehensive review of the entire tax return or full business records.
HMRC uses this when it believes there may be major inaccuracies, or there is a high risk of significant tax loss. -
Discovery Assessment - HMRC can issue a discovery assessment when new information comes to light suggesting that tax is understated, not assessed, or was insufficiently disclosed.
Often triggered by third‑party data, mismatches, or suspected fraud. -
Random Check - HMRC can randomly select any individual or business, even if everything appears correct.
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Unannounced Visit - Used typically where HMRC suspects serious evasion or believes records may be concealed or destroyed. These are less common and are generally linked to fraud‑risk cases.
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Compliance Check (General Term) - A broad term covering HMRC's reviews across different taxes—e.g., VAT assurance visits, employer compliance reviews, corporation tax checks, and self‑assessment enquiries.
How is the investigation concluded?
The outcome depends on HMRC’s findings:
- If too much tax has been paid, HMRC will issue a refund.
- If tax has been underpaid, the business must pay the outstanding amount, usually with interest from the original due date.
HMRC may also apply penalties if they identify underpaid tax or over‑claimed reliefs. Penalty levels depend on factors such as:
- Whether the error was careless, deliberate, or concealed
- Whether reasonable care was taken in preparing the tax return
- How promptly the business disclosed the issue
- The level of cooperation shown during the investigation
How to get help with an HMRC investigation
HMRC enquiries can be time‑consuming, disruptive, and costly with fees often running into tens of thousands of pounds - even when no wrongdoing has actually occurred.
However, as your accountant, Shorts can support you throughout the process. Our specialist tax team will manage all communication with HMRC, explain their requests, gather required information, and help minimise the impact on your business and personal life.
Defending a tax enquiry can lead to additional and unexpected accountancy fees. For peace of mind, you can subscribe to our Tax Investigation Service, which covers professional fees in most cases up to £100,000. If your business subscribes, directors, partners, their spouses, and company secretaries will also benefit from representation for investigations into their personal tax affairs, provided we act for them.
Steven Strawther
I deal with all aspects of personal tax compliance and since joining Shorts I have gained valuable experience in private client advisory and planning opportunities. I have been instrumental in refining the personal tax compliance process and implementing digital solutions to provide clients with an efficient personal tax service.
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