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CompC1CRYPTOMMLetter about Capital Gains Tax on cryptoassets

Published by its source on 28 October 2021. A date in the letter that has passed stays passed: what a passed date means.

Last reviewed 14 October 2026 · How Tax Letters checks its facts

In short

HMRC's letter CompC1CRYPTOMM is headed “Capital Gains Tax on Cryptoassets”. In this version the letter says HMRC has also sent a copy of it to the reader's agent.

“CompC1CRYPTOMM … Capital Gains Tax on Cryptoassets … We've also sent a copy of this letter to your agent”

CIOT: copy of HMRC letter CompC1CRYPTOMM, published on its page · checked 14 October 2026

Information, not advice: this page reports what HMRC, GOV.UK and the bodies named publish about CompC1CRYPTOMM. Each fact has its source and the day it was checked beside it.

What it is

HMRC's letter CompC1CRYPTOMM says that if the reader disposes of cryptoassets, they may have to pay Capital Gains Tax (CGT).

“CompC1CRYPTOMM … If you dispose of cryptoassets, you may have to pay Capital Gains Tax (CGT).”

CIOT: copy of HMRC letter CompC1CRYPTOMM, published on its page · checked 14 October 2026

CIOT said that the HMRC letters in this campaign, which include CompC1CRYPTOMM, would advise taxpayers that gains on cryptoassets are liable to Capital Gains Tax and highlight common types of disposal.

“The letters will advise taxpayers that gains on cryptoassets are liable to Capital Gains Tax, and highlight common types of disposal.”

CIOT: HMRC’s One to Many letter Cryptoassets project · checked 14 October 2026

When HMRC sends it

HMRC's letter CompC1CRYPTOMM says HMRC has information that indicates the reader holds, or has held, investments in cryptoassets.

“CompC1CRYPTOMM … We have information that indicates you hold, or have held, investments in cryptoassets (also known as cryptocurrency).”

CIOT: copy of HMRC letter CompC1CRYPTOMM, published on its page · checked 14 October 2026

CIOT said, on its page for HMRC's letter CompC1CRYPTOMM, that HMRC's Wealthy External Forum had issued a briefing to forum members about ‘one to many’ letters being sent to taxpayers it believed had held cryptoassets.

“HMRC’s Wealthy External Forum has issued a briefing to forum members about ‘one to many’ letters being sent to taxpayers who they believe have held cryptoassets, advising them of the potential tax implications and linking to relevant guidance.”

CIOT: HMRC’s One to Many letter Cryptoassets project · checked 14 October 2026

What it asks

HMRC's letter CompC1CRYPTOMM asks the reader to review their cryptoasset transactions, and says a reader satisfied that they have no tax to pay does not need to do anything.

“CompC1CRYPTOMM … Please review your cryptoasset transactions. … If you're satisfied that you do not have any tax to pay, you do not need to do anything.”

CIOT: copy of HMRC letter CompC1CRYPTOMM, published on its page · checked 14 October 2026

Free help and HMRC contacts

HMRC's letter CompC1CRYPTOMM points to www.gov.uk, search “Capital Gains Tax”, for more guidance.

“CompC1CRYPTOMM … For more guidance on Capital Gains Tax, go to www.gov.uk and search for 'Capital Gains Tax'.”

CIOT: copy of HMRC letter CompC1CRYPTOMM, published on its page · checked 14 October 2026

HMRC's letter CompC1CRYPTOMM says a reader whose health or personal circumstances make it difficult to deal with the matter can tell HMRC, and points to www.gov.uk/get-help-hmrc-extra-support.

“CompC1CRYPTOMM … If there's anything about your health or personal circumstances that may make it difficult for you to deal with this matter, please tell us so that we can help you in the most appropriate way. … For more details, go to www.gov.uk/get-help-hmrc-extra-support”

CIOT: copy of HMRC letter CompC1CRYPTOMM, published on its page · checked 14 October 2026

Free help first

These routes are described by GOV.UK, TaxAid and Citizens Advice themselves.

  • HMRC's extra supportHMRC offers extra support if your health condition or personal circumstances make it difficult to contact HMRC, for example a mental health condition, financial hardship or being treated in hospital.
  • Someone to deal with HMRC for youYou can authorise a friend, relative or voluntary organisation to talk to HMRC for you and help you fill in forms.
  • TaxAidTaxAid helps people with tax problems who cannot pay for advice. Tax Help for Older People merged with TaxAid in July 2025.
  • Citizens AdviceCitizens Advice gives confidential advice online, over the phone and in person, for free.