How Far Back Can HMRC Go

25 August 2023

An HMRC tax investigation has wide-reaching powers but that doesn't mean that they can go back as far as they want whenever they want. There are strict rules and regulations governing the investigation process that determine the length of time that HMRC can go back when looking into your tax affairs. If you need advice about an HMRC tax investigation or you want to ensure that your records are correct to avoid getting investigated, contact us at Auditox Accountancy for professional help and advice.

What Does An HMRC Tax Investigation Involve?

HMRC has the right to check the tax affairs of any person or company at any point. If you are an employee, then your employer is responsible for paying your tax through the PAYE system but if you are self-employed or have any other income outside of employment then you will need to submit a Self-Assessment tax return and this income tax can be investigated. As can all other types of tax, including:

  • Capital Gains Tax
  • Stamp Duty Land Tax
  • Stamp Duty Reserve Tax
  • Petroleum Revenue Tax
  • Insurance Premium Tax
  • Corporation Tax
  • Construction Industry Scheme (CIS)
  • Value Added Tax (VAT)
  • Landfill Tax
  • Climate Change Levy
  • IR35

An investigation can be triggered because HMRC's data mining team has found suspected errors in your accounts, if you work in a "high risk" industry, if there has been a tip-off about your or your company, or as part of a random check.

You will be asked to submit information related to your tax accounts. This could include:

  • expense receipts
  • bank statements
  • invoices
  • quotes

The information that HMRC will ask for will depend on the type of tax enquiry being conducted. For example, a full tax investigation will often require more information than an aspect enquiry.

There are three types of HMRC tax investigation:

  • Full enquiry
  • Aspect enquiry
  • Random check

Dig Deeper: 5 Stages Of Tax Investigation

Full Enquiry

During a full enquiry, HMRC can look into all aspects of your tax affairs, including the amount of tax you paid, all of your accounts, your Self Assessment tax return as well as your company, PAYE, and VAT tax returns where applicable.

A full enquiry is conducted when HMRC suspects that there is a significant risk of error in your accounting.

Aspect Enquiry

If HMRC suspects that there is only a risk of error in one aspect of your accounting, they will launch an aspect enquiry. This has less scope than a full enquiry and will look at only one particular aspect of your tax affairs.

Random Check

Sometimes HMRC will choose a person or company at random for a tax investigation. In this case, the depth of the investigation will depend on what HMRC uncovers.

How Far Back Can A Tax Investigation Go?

HMRC has 12 months from the date of your tax submission to launch an investigation. If this initial investigation unearths puzzling results, then they have the power to reopen previously settled tax returns.

HMRC's power to investigate your account comes from their information gathering powers laid out in Schedule 36, Finance Act 2008. The act does not specify time limits on how far back HMRC can go but a variety of court cases and tribunals have set out clear precedents that HMRC needs to abide by.

The officers will initially look at the 12 months that the investigated tax return covers. Based on their findings from this, they may be able to launch a discovery assessment. They can only do so if the officers have reason to believe that a loss of tax has been brought about carelessly or deliberately and that there would be no reasonable way for HMRC to have known about it previously.

HMRC cannot trigger a discovery assessment if the return was filed by practice prevailing. This means that they can't retrospectively investigate you if the return was filed correctly based on the rules at the time, even if it is incorrect based on current legislation.

They also can't go on a "fishing expedition" to look for errors in the previous tax year and beyond if they are unable to show evidence for why there are suspected problems.

This discovery assessment can go back for different periods depending on what HMRC has reason to suspect has happened.

  • For simple clerical accounting errors, HMRC tax investigations can look back four years.
  • For suspected careless tax returns and mistakes, HMRC can go back six years for most types of tax (apart from VAT where the limit remains at four years).
  • If they suspect deliberate tax evasion and tax avoidance, HMRC can look at tax submissions as far back as 20 years for all types of tax.

Learn more: How Likely Are You To Be Investigated By HMRC

Tax Investigations Outcomes

The length of time the investigation will take depends on the type of investigation, how big the company is, and how complicated the tax records are.

Generally speaking, an aspect enquiry won't usually last for more than six months whereas a full enquiry can last as long as a year and a half.

Once the investigation is complete, there are three possible outcomes:

  • Overpaid tax - in this case, HMRC will offer you a refund
  • Underpaid tax - in this case, you will owe HMRC money
  • Deliberate or negligent wrongdoing - In this case, you will owe HMRC money and will likely be subject to HMRC tax investigation penalties

How To Avoid A Tax Investigation

It isn't always possible to completely avoid a tax investigation because sometimes it truly is a completely random check. You can reduce your chances of being investigated, however, by ensuring that you pay tax on time, that your tax returns are submitted correctly, and that you pay the correct amount of tax.

Explore further: How To Avoid Tax On Capital Gains

If You Need Tax Investigation Advice

If you have received notice that HMRC will be investigating your taxes or you want to ensure that your tax return and records are fully up to date and correct to avoid being investigated, Auditox Accountancy can help you.

Our team of experienced accounting professionals understands UK tax law inside and out and can advise you on all areas of tax, even if your tax situation is complicated.

Uncover more: Closing A Limited Company With Debts To HMRC

Final Thoughts

An HMRC tax investigation can be a stressful time but some strict rules and regulations govern how far back HMRC can investigate your taxes. The investigation must be triggered within 12 months of your tax return being filed and they can look back at previous tax returns for four years in the case of innocent errors, six years for careless mistakes (except for VAT which remains at four years), and 20 years for deliberate tax evasion and avoidance.

What are we

Contact us
Copyright © 2025 auditox-accountancy.uk
Privacy policy
Terms and conditions
Legal information and disclaimer