How Likely Are You to be Investigated by HMRC?

Technically, all businesses are at risk of being investigated by HMRC due to random selection; 7% of tax investigations per year are selected at random. But, In most cases, tax investigations are triggered through some kind of wrongdoing, mistakes on accounts, or through a tip-off. 

So, how likely are you to be investigated by HMRC? 7% of all HMRC tax investigations are randomly selected, therefore all businesses, even if they haven’t done anything wrong, are at risk of being randomly selected for a HMRC tax investigation. However, you’re more likely to be investigated if your accounts are incorrect, or you are suspected of wrongdoing. 

Read on to learn more about the likelihood of being selected for a HMRC tax investigation, as well as what can trigger a HMRC tax investigation, and how long they can take.

How Likely Are You to Be Investigated by HMRC?

Since 7% of all HMRC tax investigations are randomly selected, any business—even those that have done nothing wrong—could be chosen. However, the likelihood of an investigation increases if your accounts contain errors or if there is suspicion of wrongdoing.

Read on to learn more about the likelihood of being selected for a HMRC tax investigation, what can trigger one, and how long the process takes.

“HMRC now receives international banking data under global information sharing agreements. One of our clients received a letter saying they had discovered undisclosed foreign interest income in this case, from fixed deposits in India.

Her previous accountant had never informed her that UK tax residents must declare worldwide income. We helped her prepare a disclosure, calculating interest, penalties, and the additional tax owed for several years. HMRC hasn’t responded yet, but we expect the matter to be resolved similarly with tax and penalties paid, and no further consequences.

This case highlights the importance of proper advice, especially for clients with overseas assets or accounts.”

Saurabh Bedi

Director, ARB Accountants

How Common are HMRC Investigations?

Only 7% of all HMRC tax investigations are random checks that aren’t triggered by wrongdoing, or any kind of suspicious activity. However, if your tax return looks a little odd, even just one element of it, that could trigger a tax investigation. 

Some claim that HMRC have an annual quota of tax investigations to achieve which, true or not, could provide insight into why so many individuals and businesses are investigated for small mistakes on their tax returns, or minor inconsistencies. That being said, you’re more likely to be picked up for investigation due to inconsistencies and criminal activity. 

However, if your business is VAT registered or has PAYE employees, you should still expect routine tax audits every 5 years or so. 

What Are the Chances of Being Investigated by HMRC?

If you’re wondering what are the chances of being investigated by HMRC, the answer depends on various factors. While some businesses and individuals are selected at random, most tax investigations are triggered by discrepancies in tax returns, unusual expense claims, or undeclared income.

Certain industries, particularly those dealing in cash transactions, face a higher likelihood of being investigated. If HMRC spots irregularities in your accounts, such as a significant drop or spike in income, it could lead to further scrutiny. Ensuring accuracy in your tax filings can help reduce how likely you are to be investigated by HMRC.

What Triggers HMRC Investigation?

Since such a small portion of tax investigations are random, you might be wondering what can trigger a HMRC tax investigation. Generally, tax investigations are triggered by inconsistencies in tax returns, mistakes, late payments, and tip-offs.

A HMRC tax investigation may be triggered by:

• Lateness in filing tax returns or making payments
• Errors on your tax return
• Inconsistencies or substantial variations between different tax returns. This could be a large rise or fall in income or costs
• Abnormally high costs for your industry
• The tax return is inconsistent with how your business is performing, or with your standard of living
• You have offshore accounts
• You have income from property
• You operate in a high-risk industry
• A tip-off

“A client unknowingly failed to declare rental income from a second property. HMRC discovered it through a combination of land registry and council tax data. They knew he wasn’t living there and assumed rightly that it was being rented out.
He received a letter inviting him to disclose the income voluntarily. We went back through five years of records, calculated the unpaid tax, interest, and penalties, and submitted a full disclosure. HMRC accepted our offer, and the case was closed.
This case shows that HMRC has access to cross-government data and rental income is a common red flag.”

Saurabh Bedi

Director, ARB Accountants

How Do HMRC Decide Who to Investigate?

Many businesses and individuals ask, how do HMRC decide who to investigate? HMRC uses a combination of data analysis, risk assessments, and reports from third parties to identify potential tax discrepancies. They cross-check tax returns with banking records, property ownership, and even online transactions.

Common triggers for an HMRC investigation include undeclared income, repeated late tax filings, or expenses that seem abnormally high for your industry. In some cases, HMRC may receive a tip-off or notice patterns that suggest potential tax evasion. While random checks do occur, ensuring compliance with tax regulations significantly reduces how likely you are to be investigated by HMRC.

READ RELATED ARTICLE: Do I need to register for self-assessment?

Do HMRC Do Random Checks?

HMRC does conduct random checks at a rate of 7% per year. However, they will not turn up unannounced; HMRC will usually contact you beforehand by phone or post to request various pieces of information, and to schedule a visit. It is important to respond to any HMRC correspondence about tax investigations as soon as possible in order to avoid penalties.

What Happens During an HMRC Tax Investigation?

If HMRC opens an investigation into your tax affairs, the process usually begins with a formal letter. This letter outlines what they’re reviewing — whether it’s a specific part of your tax return or a broader examination of your overall finances. Depending on the scope, they might request supporting documents such as bank statements, sales records, VAT filings, payroll data, or contracts.

Once the initial request is made, HMRC may:

• Ask for records to be sent digitally or by post
  
• Schedule a phone call or in-person meeting
  
• Visit your business premises or, in some cases, your home
  
• Interview you or your accountant regarding the accounts in question
  

During the investigation, HMRC is focused on confirming the accuracy of the information you’ve reported. The process can feel intrusive, but having accurate documentation and a trusted accountant on your side can make it significantly more manageable. Investigations may result in no further action, adjustments to tax owed, or penalties if errors are found. That’s why knowing how HMRC decides who to investigate and keeping clean records can make a major difference.

“One of our clients had sold her business after 20 years and claimed Business Asset Disposal Relief on her tax return, saving a significant amount in tax by paying only 10%. About 12 years later, HMRC sent a compliance check letter asking for clarifications. We prepared a response with all documentation, answered follow-up questions, and the case was closed successfully with no penalties. It’s important to note this wasn’t a full-blown investigation. HMRC didn’t accuse her of wrongdoing they just wanted to verify the claim. This is a good example of a compliance check that looked serious but was resolved smoothly.”

Saurabh Bedi

Director, ARB Accountants

When Does HMRC Investigate the Self-Employed?

Many self-employed individuals handle their own tax reporting, which increases the risk of errors. If you’re self-employed, you might wonder, when does HMRC investigate self-employed professionals? HMRC typically investigates when they detect inconsistencies in reported earnings, unusually high expenses, or late tax filings.

If your declared income doesn’t match your standard of living, or your expenses seem excessive compared to industry norms, it could trigger an HMRC investigation. Freelancers, tradespeople, and cash-based businesses are especially at risk. To avoid issues, it’s essential to keep accurate financial records and file tax returns on time.

How Do I Know If HMRC Are Investigating Me?

HMRC will not turn up out of the blue to conduct a tax investigation; you will be notified by phone or post when HMRC opens a case on your business. They will either request information or simply inform you that an investigation has been opened. 

However, the type of investigation opened depends on whether HMRC is conducting a random check, or what they suspect you of:

• Full Enquiry – HMRC will review the entirety of your business records under the belief that there is a significant risk of an error in your tax. This may also be triggered by criminal activity
• Aspect Enquiry – HMRC will look at a particular aspect of your accounts, such as inconsistencies
• Random Check – Random Checks can happen at any time to any business, not necessarily because of mistakes or wrongdoing

How Long Does it Take HMRC to Investigate Someone?

The duration of an HMRC tax investigation varies based on its scope:

• Small investigations: 3-6 months
• Full-scale investigations: Up to 16 months

Providing full compliance and responding swiftly to HMRC requests can help shorten the investigation timeline.

READ RELATED ARTICLE: How to make a voluntary disclosure to HMRC

How to Reduce the Chances of an HMRC Investigation

While tax investigations are selected at random, the majority are triggered by inconsistencies, late filings, or unusual patterns. To lower your chances of being investigated by HMRC, it’s worth tightening up your financial habits and tax reporting.

Here’s how:

• Keep your records clean and consistent: Use cloud-based accounting tools to maintain clear, well-organised financial data.
  
• Double-check all income is declared: Omitting rental income, freelance earnings, or dividends increases the risk.
  
• Stay up to date with tax rules for your industry: Especially if you’re self-employed or run a cash-based business — when HMRC investigates the self-employed, it’s often due to industry-specific risks.
  
• Avoid claiming non-allowable expenses: Only include deductions that HMRC permits for your profession.
  
• Get your return reviewed by a professional: Even if you handle bookkeeping yourself, an accountant can catch red flags before HMRC does.
  

Understanding what are the chances of being investigated by HMRC depends largely on how accurate and transparent your tax submissions are. Taking a proactive approach not only gives peace of mind but may help avoid the stress of an enquiry altogether.

“One client had a PAYE job and some rental income, so we submitted a self-assessment. He forgot to mention that he had an outstanding student loan, so it wasn’t included in the return. HMRC noticed the omission and sent a letter. We replied, explaining it was a genuine oversight, and because it was his first error, they allowed us to correct it without penalties. These types of cases are surprisingly common people forget to tick the student loan box or assume their employer has handled it. It’s a simple mistake, but still triggers inquiries.”

Saurabh Bedi

Director, ARB Accountants

Tax Advice Southend

ARB Accountants offers a range of tax advice in Southend, including for tax investigations and tax audits. Our chartered accountants in Southend will help to remove the worry and stress from your HMRC investigation, whether you’re facing a single issue dispute, formal enquiry, special enquiry, or just a random check. 

Get in touch with us today to see how we can help ease the burden of a HMRC tax investigation, as well as saving you time and, potentially, a lot of money.

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