How many years a voluntary disclosure must cover

Q: How do Inheritance Tax and VAT differ?

Inheritance Tax. HMRC's guide says that if an Inheritance Tax return was never submitted and the tax never paid, you must pay what you owe for the previous 20 years whatever the reason, and if the tax was deliberately not paid there is no time limit. VAT. VAT cannot be disclosed through the Digital Disclosure Service; HMRC's guide points to correcting errors on a VAT return where the conditions allow, or notifying them on form VAT 652 or by letter. The time limits are in section 77 of the Value Added Tax Act 1994: 4 years after the end of the prescribed accounting period, or 20 years for a deliberate loss, for knowing participation in fraudulent arrangements, or for a failure to comply with a registration obligation. Section 77 contains no separate 6 year limit for carelessness, so a careless VAT error stays within the ordinary 4 years.

Q: What mistakes do people make?

Choosing careless to shorten the period. HMRC reviews the behaviour label and may reject the disclosure or open a check if it disagrees. Counting from the date of the disclosure. Each limit runs from the end of the tax year or accounting period, not from today. Missing the offshore element. A single foreign account can extend a careless case from 6 to 12 years for that income. Leaving it too long. HMRC's guide says that where correction has taken a significant period, normally over 3 years, it is unlikely to reduce a penalty by more than 10 percentage points above the minimum. The routes and penalties are covered on making a voluntary disclosure. If HMRC opens a check into your return, tax investigation insurance pays your accountant's fees. Solar Protect cover pays up to £100,000 with no excess; it never pays tax, interest or penalties. Read how our cover works or get a quote.

A voluntary disclosure has to go back as far as HMRC could assess the tax, and that depends on why the tax was underpaid. HMRC’s own guide sets the maximum at 4 years where you took reasonable care, 6 years where you were careless and 20 years where you acted deliberately or never registered, while income or gains with an offshore element can stretch a non deliberate case to 12 years.

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Where do the 4, 6 and 20 year limits come from?

The disclosure periods mirror the statutory time limits for assessments: you disclose the years HMRC could still assess if it found the problem itself. For Income Tax and Capital Gains Tax the rules are in the Taxes Management Act 1970:

Section 34 sets the ordinary limit: an assessment may be made not more than 4 years after the end of the tax year it relates to.
Section 36(1) extends this to 6 years where the loss of tax was brought about carelessly.
Section 36(1A) extends it to 20 years where the loss was brought about deliberately, or is attributable to a failure to notify chargeability under section 7, or to certain failures under the disclosure of tax avoidance schemes rules.

Section 36(1B) treats a loss brought about by someone acting on your behalf as brought about by you, so an agent’s carelessness can extend your period too. Our page on adviser carelessness and time limits covers that point.

Companies follow the same pattern under paragraph 46 of Schedule 18 to the Finance Act 1998: 4 years after the end of the accounting period, 6 years for a careless loss and 20 years for a deliberate loss or a failure to notify chargeability. The general picture of assessing limits is on how far back HMRC can go.

How do you decide which behaviour applies?

HMRC’s guide Make a voluntary disclosure to HMRC says the number of years depends on whether the error was made despite taking reasonable care, because you were careless, or deliberately, and whether the lost tax involves an offshore matter or transfer. It defines deliberate as knowing you owed tax but choosing not to tell HMRC, or knowing the figures on your return were wrong when you sent it.

The decision is yours to make, and it carries weight. The Worldwide Disclosure Facility guidance asks you to self assess your behaviour, presents the years to include based on that choice, and warns that an incomplete or incorrect self assessment of behaviour may lead to a civil intervention or a criminal prosecution. One disclosure can contain careless years and deliberate years.

HMRC also signals where it will test the label. Its guide gives the example that it may not accept that someone in business for many years, earning significant amounts without telling HMRC, has not acted deliberately. If HMRC thinks the penalty in the disclosure is too low, it may carry out a further check.

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Which years go in the disclosure and which go on a tax return?

The most recent years are usually not in the disclosure at all. HMRC’s guide says income from the current tax year should be reported on the next tax return, and income from the year before the current year should go on that year’s return. The disclosure covers the earlier years.

For someone registered for Self Assessment, the guide spells out the count:

Behaviour	Maximum period	What goes in the disclosure
Reasonable care	4 years	The 3 years before the year that goes on a return
Careless	6 years	The 5 years before the year that goes on a return
Deliberate, or failure to register for Self Assessment on time	20 years	Every year back to the start of the problem, within 20 years
Offshore matter or transfer, non deliberate	12 years	Subject to the earliest years HMRC names (see below)

As at October 2026, HMRC’s guide says a disclosure can cover tax years up to and including 2024 to 2025, but any return HMRC has issued for 2022 to 2023 onwards that is still outstanding must be filed rather than included. For companies, the guide says outstanding Company Tax Returns within 4 years of the end of the accounting period should be filed, with earlier years going in the disclosure.

How does the offshore 12 year rule change the count?

Section 36A of the Taxes Management Act 1970 allows an assessment up to 12 years after the end of the tax year where lost Income Tax or Capital Gains Tax involves an offshore matter, or an offshore transfer that makes the lost tax significantly harder to identify. An offshore matter includes income from a source outside the UK, assets held outside the UK and activities carried on wholly or mainly outside the UK. The 20 year limit for deliberate cases still applies on top.

HMRC’s guide says that where reasonable care was taken, the earliest year it reaches is 2015 to 2016, and where the behaviour was careless the earliest year is 2013 to 2014. The guide applies the offshore rules to Income Tax (including PAYE), Capital Gains Tax and Inheritance Tax.

There is an exception in section 36A(7): the 12 year limit does not apply if, before the normal limit expired, HMRC received information from an overseas authority from which it could reasonably have been expected to spot the lost tax, and it was reasonable to expect an assessment within the normal limit. Offshore disclosures are made through the Worldwide Disclosure Facility, and the detail of the rule is on our page about the 12 year offshore time limit.

How do Inheritance Tax and VAT differ?

Inheritance Tax. HMRC’s guide says that if an Inheritance Tax return was never submitted and the tax never paid, you must pay what you owe for the previous 20 years whatever the reason, and if the tax was deliberately not paid there is no time limit.

VAT. VAT cannot be disclosed through the Digital Disclosure Service; HMRC’s guide points to correcting errors on a VAT return where the conditions allow, or notifying them on form VAT 652 or by letter. The time limits are in section 77 of the Value Added Tax Act 1994: 4 years after the end of the prescribed accounting period, or 20 years for a deliberate loss, for knowing participation in fraudulent arrangements, or for a failure to comply with a registration obligation. Section 77 contains no separate 6 year limit for carelessness, so a careless VAT error stays within the ordinary 4 years.

What if you never registered or never filed?

A failure to notify chargeability falls within section 36(1A)(b), which is why HMRC’s guide says anyone who did not register for Self Assessment by the appropriate deadline will have to pay what they owe for up to 20 years. The guide gives the deadline for an individual as 5 October in the business’s second tax year; for tax on income in the year ended 5 April 2026, HMRC should have been told by 5 October 2026.

The Worldwide Disclosure Facility form lists a failure to notify with a reasonable excuse as a separate behaviour from one without, so the reason for not registering should be recorded accurately rather than assumed.

Does a COP9 disclosure cover a different period?

Yes, in practice it is the longest. Code of Practice 9 says that entering a Contractual Disclosure Facility contract is an admission of deliberate behaviour, so HMRC can recover tax, interest and penalties for up to 20 years, or longer where legislation exceptionally permits. HMRC’s Fraud Civil Investigation Manual at FCIM206040 says HMRC does not agree a period with the taxpayer: the report covers the period in which the fraud occurred, theoretically without limit and in practice up to 20 years, and that period should already appear in the outline disclosure.

How might the count work in practice?

Illustration only. A self employed consultant has been registered for Self Assessment throughout but has under reported fees since 2018 to 2019 through poor record keeping. She discloses in October 2026, during the 2026 to 2027 tax year.

Her 2025 to 2026 income goes on the return for that year, due online by 31 January 2027.
Treating the behaviour as careless, the disclosure covers the 5 years before that: 2020 to 2021 through 2024 to 2025.
2018 to 2019 and 2019 to 2020 fall outside the 6 year limit and are left out.
If she also had untaxed interest on an overseas bank account, the offshore rule reaches back to 2013 to 2014 for careless behaviour, so the earlier years of that interest come back in.
If the facts show she knew the fees were missing, the behaviour is deliberate and every year back to 2018 to 2019 must be disclosed.

What mistakes do people make?

Choosing careless to shorten the period. HMRC reviews the behaviour label and may reject the disclosure or open a check if it disagrees.
Counting from the date of the disclosure. Each limit runs from the end of the tax year or accounting period, not from today.
Missing the offshore element. A single foreign account can extend a careless case from 6 to 12 years for that income.
Leaving it too long. HMRC’s guide says that where correction has taken a significant period, normally over 3 years, it is unlikely to reduce a penalty by more than 10 percentage points above the minimum. The routes and penalties are covered on making a voluntary disclosure.

If HMRC opens a check into your return, tax investigation insurance pays your accountant’s fees. Solar Protect cover pays up to £100,000 with no excess; it never pays tax, interest or penalties. Read how our cover works or get a quote.

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Sources

Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 24 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.