How far back can HMRC go in a tax investigation?

When you’re under investigation by HMRC, the rules governing how far back they can go are complex and can vary depending on a range of factors, including the type of taxes involved, the taxpayer’s behaviour and whether or not a tax return as been filed.

When HMRC discovers a loss of tax, they can usually look back at earlier years to check whether the same or similar errors occurred.

In general, HMRC can make an assessment to recover the lost tax up to four years from the end of the tax year in question. This applies to all taxes.

This is referred to as the ‘ordinary time limit’ as set out in Section 34 of the Taxes Management Act 1970.

However, there are several circumstances where the ordinary time limit is extended to six, 12 or even 20 years.

1. Cases of carelessness

For direct taxes, if HMRC believes that an inaccuracy in a return was due to the taxpayer, or someone acting on their behalf, acting carelessly, the assessing time limit can be extended to six years.

Careless behaviour for tax purposes means failing to take reasonable care – essentially not doing what a prudent and reasonable person would do when handling their tax affairs.

These extended time limits often apply where a taxpayer has made repeated errors, neglected to keep adequate records, or failed to take appropriate advice.

Where HMRC alleges careless behaviour (or worse), penalties are likely to be charged.

2. Fraudulent or deliberate actions

When HMRC suspects deliberate behaviour, fraud or tax evasion, the investigation can often be extended to look at the last 20 years.

For example, where businesses have deliberately under-reported income or inflated expenses, HMRC may choose to investigate further back in time, using its powers under Section 36 of the Taxes Management Act 1970.

In these situations, an investigation can be highly damaging, both financially and reputationally. Extending the scope to cover many years dramatically increases the amount of work required to address HMRC’s concerns.

Records become harder to obtain, memories fade, and the individuals involved in past transactions may no longer be available. And naturally, if HMRC pushes the review back as far as 20 years, the potential tax exposure is likely to rise significantly.

It’s also important to remember that penalties for deliberate behaviour are substantially higher than those for carelessness.

Any allegation of deliberate conduct should therefore be treated with the utmost seriousness and challenged robustly wherever possible.

3. Offshore matters

The 12-year time limit applies where tax relating to an offshore matter or offshore transfer has been underpaid. This applies even where reasonable care has been taken to ensure tax returns are correct.

HMRC’s access to overseas financial data is expanding rapidly, leaving far fewer places for offshore issues to hide.

Penalties relating to offshore matters are usually more severe. In extreme cases, HMRC can charge penalties up to 200% of the unpaid tax.

4. Failure to Notify

Failure to notify means a taxpayer did not tell HMRC about becoming liable to tax by the statutory deadline. When this failure leads to a loss of tax, HMRC can use extended assessment time limits.

HMRC has up to 20 years from the end of the relevant tax period to raise an assessment where tax has been lost due to a failure to notify. This 20‑year limit applies whether or not the failure was deliberate.

In practice, that often means HMRC may look at and ask questions about the full period since the business began.

Key takeaways

HMRC’s ability to look back and investigate your tax affairs is governed by a clear set of rules, with varying time frames depending on the seriousness of the situation.

While the general time limit is four years, businesses and individuals involved in more serious cases of tax non-compliance, such as fraud or offshore irregularities, can face much wider investigations.

• Four years is the ordinary time limit for HMRC assessments unless there is evidence of carelessness, fraud, or deliberate evasion.
• If HMRC believes the taxpayer has been careless, it can extend the investigation to six years.
• In cases of deliberate behaviour or Failure to Notify, HMRC can extend the investigation period to 20 years.
• Widening the scope on an enquiry can lead to a longer, more expensive and more stressful investigation.

If you’re facing a tax enquiry, particularly one involving allegation of deliberate behaviour or complex issues like offshore assets, seeking advice from a tax investigations specialist can help to limit the scope of HMRC’s investigation and protect your interests.

If you are worried about a tax investigation being launched against you, please speak to our experts.

You can get in touch with our friendly and experienced team on: 0203 675 8122 or email joe.mcdermott@intaxltd.com.

inTAX is a specialist tax disputes firm. We deal with disclosures, investigations, and tax enquiries of all descriptions, including COP9, fraud investigations, VAT fraud, tax avoidance, let property disclosures and tribunal appeals. However, we don’t just deal with the serious end of tax investigations; we are also happy to handle smaller enquiries, disputes and problems that can be equally as worrying for our clients