The guidance, which was first published in September last year, covers how individuals and companies can use the digital disclosure service to report their failure to pay the correct amount of income tax, capital gains tax, National Insurance contributions, or corporation tax.

The digital disclosure service is to be used in circumstances where the individual or company does not have the option to disclose under a specific HMRC campaign or the worldwide disclosure facility.  Each individual or company must make a separate notification.

Agents are also able to notify clients’ disclosures via the digital disclosure service.  Individuals, companies and agents who make a disclosure will be sent a unique disclosure reference number to be used for all contacts with HMRC, and a payment reference number.

Disclosures can be made as soon as the disclosure reference number is issued, and must be made within 90 days of the date that HMRC acknowledged the notification.

The guidance provides links to an online calculator and Companies House information designed to help individuals and companies calculate how much tax they owe. Where records are missing, HMRC advice is that estimates should be provided.

The number of years that individuals and companies need to disclose depends on their understanding of when they should have told HMRC about getting the income or gain.

Anyone who failed to register for a self assessment tax return by the appropriate deadline will have to pay HMRC tax owed up to a maximum of 20 years. Those judged to have taken ‘reasonable care’ will have to pay up to four years’ tax, and those were careless, a maximum of six years.

The guidance covers the implications of such disclosures relating to PAYE, tax credits and inheritance tax. It also sets out the penalty regime, explaining that for those who are found to have taken a ‘significant period’ to correct non-compliance, it is unlikely that HMRC will reduce the penalty by more than 10 percentage points above the minimum of the statutory range. For this purpose HMRC would normally consider a ‘significant period’ to be over three years, or less where the overall disclosure covers a longer period.

HMRC also points out that an important factor when deciding whether to carry out civil or criminal investigations into cases of fiscal fraud, is whether the taxpayer has made a full and unprompted disclosure of any amounts evaded or improperly reclaimed. A full and unprompted disclosure would suggest that a civil, rather than criminal, investigation was appropriate.

Guidance: Your guide to making a disclosure is here.