How far back HMRC can assess unpaid VAT

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HMRC normally has four years from the end of the relevant VAT period to assess unpaid VAT. The limit can be 20 years for deliberate behaviour, failure to notify a VAT registration liability, or certain transactions linked to a known VAT-loss arrangement.

Situation	Assessment limit	Extra condition
Normal VAT error	4 years	Measured from the end of the relevant period
Careless VAT error	4 years	Carelessness does not extend the VAT limit
Deliberate VAT error	20 years	Measured from the end of the relevant period
Failure to notify VAT registration	20 years	Applies regardless of behaviour
Assessment more than two years after period end	12-month evidence rule applies	Within 12 months of HMRC gaining evidence of facts
Eligible error corrected on next VAT Return	Previous 4 years	Net error must meet the correction limits

The normal four-year VAT limit

HMRC’s normal limit is four years from the end of the relevant prescribed accounting period. VAT Act 1994, section 77 sets the rule, with changes made by Finance Act 2008 Schedule 39.

A careless VAT error does not create a six-year assessment period. HMRC Compliance Handbook guidance lists a six-year careless limit for several taxes, but VAT is not among them.

The four-year rule covers output tax that was under-declared and input tax that was over-claimed. Errors made despite reasonable care also sit within the same four-year window.

For under-claimed input tax, the clock runs from the due date for the VAT Return rather than the accounting period end. HMRC’s VAT Assessments and Error Correction manual makes that distinction for errors involving reasonable care or carelessness.

Importation or acquisition can use a different starting point. In those cases, the four-year period can run from the date of importation or acquisition.

The assessment date matters. HMRC must make the assessment while the relevant period still falls within the four-year window.

When HMRC can reach back 20 years

HMRC can assess VAT for up to 20 years where behaviour was deliberate. It counts 20 years starting at the close of the relevant tax period.

A 20-year limit also applies where a person failed to notify liability to register for VAT. This applies whatever the person’s behaviour.

Late registration means VAT is due on sales from the date when registration became necessary.

There is another 20-year ground for a person involved in a transaction they knew, or should have known, formed part of arrangements causing a VAT loss. That ground also runs from the accounting period end or from importation or acquisition.

For periods that ended by 31 March 2010, HMRC may use the 20-year failure-to-notify route only if a penalty resulted from the failure.

The 12-month evidence of facts rule

The 12 months evidence of facts rule applies where HMRC makes an assessment more than two years after the period ended. In that situation, HMRC must make the assessment within 12 months of receiving evidence of the facts behind it.

This rule applies alongside the four-year and 20-year limits. It can shorten the available period, but it cannot replace or extend the main assessment deadline.

Consider an example. A VAT period ends on 30 June 2022, so the normal four-year deadline is 30 June 2026.

If HMRC receives the evidence on 15 September 2025, the 12-month deadline is 15 September 2026. The earlier deadline is 30 June 2026, so HMRC would need to assess by that date.

If HMRC instead receives the evidence on 1 February 2024, the 12-month deadline is 1 February 2025. That earlier date would control because the assessment is more than two years after the period ended.

HMRC Compliance Handbook guidance gives an older example involving a quarter ending on 31 October 2006. A visit found under-declared output tax on 31 August 2010, but the assessment still had to be made by 31 October 2010 because the four-year limit came first.

What HMRC may add to the VAT bill

Unpaid VAT can carry late payment interest. For accounting periods beginning on or after 1 January 2023, it runs from the first day payment becomes overdue until the debt is paid in full.

HMRC’s published rate is 7.75 per cent from 9 January 2026. The separate default interest table gives 7.75 per cent in its 9 January 2026 entry for VAT periods that began by 31 December 2022.

The rules on VAT late-payment penalties and interest cover late payment interest and related penalties.

The penalty regime in Finance Act 2007 Schedule 24 applies to VAT return inaccuracies where the return was due from 1 April 2009, for periods that started from 1 April 2008.

The penalty is calculated from Potential Lost Revenue (PLR), meaning the extra tax due once the error is corrected. The maximum penalty is 30 per cent for careless behaviour, 70 per cent for deliberate behaviour, and 100 per cent where the behaviour was deliberate and concealed.

There is no penalty where the inaccuracy happened despite reasonable care. A careless error can have a nil penalty after an unprompted disclosure.

For deliberate inaccuracies, an unprompted disclosure has a minimum penalty of 20 per cent. For deliberate and concealed inaccuracies, the unprompted minimum is 30 per cent.

A prompted disclosure has minimum penalties of 35 per cent for deliberate behaviour and 50 per cent for deliberate and concealed behaviour. The maximum still depends on the behaviour involved.

Correcting errors before HMRC assesses them

Some VAT errors from the preceding four years can be corrected through the next VAT Return. The test uses the net value of the errors, not each error separately.

Start with extra tax due to HMRC, then subtract tax due back to the business. Deliberate errors must be left out of that calculation and reported separately.

A net error of £10,000 or less can be corrected on the next VAT Return. An error between £10,000 and £50,000 can also go on the next return if it is less than 1 per cent of total sales.

For example, a business owes HMRC £18,000 from errors but is due £4,000 from other errors. Its net error is £14,000.

If total sales are £2,000,000, 1 per cent is £20,000. The £14,000 net error is below £20,000 and below £50,000, so it meets the stated middle-band test.

Net errors above £50,000 must be reported separately to HMRC. The same applies where the net error exceeds £10,000 and is more than 1 per cent of total sales.

Deliberate errors always need separate reporting. Businesses correcting ordinary input tax errors may also need to check which VAT on business costs can be reclaimed.

VAT record-keeping periods and recovery proceedings

VAT records must be retained for at least six years. The period is 10 years for businesses using VAT One Stop Shop (OSS), and for anyone who used VAT Mini One Stop Shop (MOSS).

A 20-year assessment window can extend 14 years beyond a six-year record requirement, or 10 years beyond a 10-year requirement.

In England and Wales, Limitation Act 1980, section 37(2) excludes tax, duty and related interest recovery proceedings from a time limit.

In Scotland, Prescription and Limitation (Scotland) Act 1973, section 7 gives a 20-year limit for summary warrant proceedings.

Common questions

Does a careless VAT error give HMRC six years?

No. Careless VAT errors remain within the normal four-year limit, unlike some other taxes.

Can HMRC assess unpaid VAT after four years?

Yes, where deliberate behaviour applies, where VAT registration liability was not notified, or where the transaction meets the VAT-loss arrangement condition. Those grounds can allow 20 years.

Does the 12-month rule give HMRC an extra year?

No. It restricts HMRC once an assessment is more than two years after period end. It cannot extend the four-year or 20-year deadline.

Can every old VAT error go on the next VAT Return?

No. The error must be from the preceding four years and fall within the net-value limits. Deliberate errors must be reported separately.

Sources

• GOV.UK: CH51300 - Assessing Time Limits: The Time Limits: What are the new time limits - introduction - HMRC internal manual
• GOV.UK: CH56300 - Assessing Time Limits: Tables of time limits for relevant taxes: VAT - HMRC internal manual
• GOV.UK: VAEC7410 - Error correction for VAT returns: Time limits: Introduction - HMRC internal manual
• GOV.UK: CH51530 - Assessing Time Limits: The Time Limits: When the new time limits take effect: VAT - extended time limits and transitional provisions - HMRC internal manual
• GOV.UK: CH51820 - Assessing Time Limits: VAT Limitations: Tax assessments - HMRC internal manual
• GOV.UK: DMBM595080 - Pre-enforcement: limits in enforcement proceedings: limitation legislation - HMRC internal manual
• GOV.UK: DMBM595070 - Pre-enforcement: limits in enforcement proceedings: summary warrant (Scotland) - HMRC internal manual
• GOV.UK: Sending a VAT Return: Late returns and payment
• GOV.UK: HMRC interest rates for late and early payments
• GOV.UK: CH81012 - Penalties for inaccuracies: in what circumstances is a penalty payable: commencement date - part 1 - HMRC internal manual
• GOV.UK: CH82120 - Penalties for Inaccuracies: Calculating the penalty: Amount of Penalty - introduction - HMRC internal manual
• GOV.UK: CH82160 - Penalties for Inaccuracies: Calculating the Penalty: Potential Lost Revenue: Single inaccuracy - HMRC internal manual
• GOV.UK: CH82470 - Penalties for Inaccuracies: Calculating the Penalty: Penalty reductions for quality of disclosure: Maximum and minimum penalties for each type of behaviour - HMRC internal manual
• GOV.UK: CH82420 - Penalties for Inaccuracies: Calculating the Penalty: Penalty reductions for quality of disclosure: Unprompted and prompted disclosure - HMRC internal manual
• GOV.UK: CH81130 - Penalties for Inaccuracies: Types of inaccuracy: Inaccuracy despite taking reasonable care - HMRC internal manual
• GOV.UK: Register for VAT: When to register for VAT
• GOV.UK: Sending a VAT Return: Correct errors in your VAT Return
• GOV.UK: Charge, reclaim and record VAT: Keeping VAT records