HMRC has analysed thousands of tax returns and identified people who have not paid capital gains tax on the sale of shares, giving them 60 days to respond to the latest letter campaign.

A failure to reply within the deadline will lead to HMRC opening an enquiry into the taxpayer. Even if the taxpayer is confident that they do not owe any tax, they must write and tell HMRC why the gains are not due.

Note that HMRC requires an old school letter through the post so ensure you pay for proof of posting through the Post Office and keep a copy of all correspondence.

The ‘one to many’ letters have been sent to individual taxpayers and their accountants or tax agents, setting out the next steps. They also tell people to seek professional advice if they don’t already do so.

HMRC stated: ‘Our information shows that you disposed of your shares in [company names from data file] in [date]. You may have to pay capital gains tax (CGT) on this disposal of shares.’

HMRC is reminding taxpayers that they must pay CGT if their total chargeable gains from all disposals in a tax year are over the annual exempt amount.

For tax years 2020-21 to 2022-23, the annual exempt amount was £12,300 for individuals, personal representatives and trustees for disabled people. The exemption was £6,150 for other trustees.

This was halved for the last tax year, running at £6,000 for 2023-24, and will be reduced to £3,000 for 2024-25.

The ‘total chargeable gain’ is normally the difference between what was paid for the shares and what they were sold for.

HMRC added: ‘If you make or made a loss, you may be able to use this to reduce the CGT due on other gains. If you have an agent, we have sent them a copy of this letter. If you don’t have an agent, you may wish to seek professional advice.

‘If you need to amend your return, you must do so within 60 days of the date of this letter. If you don’t, we may open an enquiry.’

Taxpayers can settle any outstanding tax – but if they fail to do so and HMRC carries out a compliance check in the future and finds that your tax return is not correct, penalties are likely to be charged.

HMRC also said that taxpayers could be charged penalties regardless if they have failed to pay the correct tax. ‘We may also do this if you’ve not told us that you need to pay additional tax,’ HMRC stressed at the end of the letter.