CompC1OMSCMMLetter about income from online marketplace sales

HMRC's letter CompC1OMSCMM tells the reader HMRC has information that shows they earned income from online marketplace sales up to the tax year ending 5 April 2023.

“CompC1OMSCMM … We have information that shows you’ve earned income from online marketplace sales up to the tax year ending 5 April 2023. You need to tell us about this income.”

ICAEW: HMRC letter CompC1OMSCMM, as published with its tax news item · checked 14 October 2026

ICAEW said, in the news item with HMRC's letter CompC1OMSCMM, that HMRC was writing to individuals who might have tax to pay on online marketplace sales made in 2022/23 and earlier tax years.

“HMRC is writing to individuals who may have tax to pay on online marketplace sales made in 2022/23 and earlier tax years.”

ICAEW: Online marketplace sellers may have tax to pay · checked 14 October 2026

HMRC's letter CompC1OMSCMM asks the reader to declare any income or contact HMRC.

“CompC1OMSCMM … Please declare any income or contact us.”

ICAEW: HMRC letter CompC1OMSCMM, as published with its tax news item · checked 14 October 2026

ICAEW said, in the news item with HMRC's letter CompC1OMSCMM, that the letter asks a person with income to declare, and a person with none, to take action within 30 days of the date of the letter: by following the instructions on gov.uk or calling HMRC if there is income to declare, or by contacting HMRC by phone or email if not.

“Where the person has income to declare, they should … follow the instructions on gov.uk … or call HMRC using the number given in the letter. If they don’t have income to declare, they should contact HMRC by phone or email using the details provided. In both cases, the letter says they should take action within 30 days of the date of the letter”

ICAEW: Online marketplace sellers may have tax to pay · checked 14 October 2026

HMRC's letter CompC1OMSCMM names the GOV.UK service “Tell HMRC about underpaid tax from previous years” and the phone number 0300 123 0998 for a reader with income to declare.

“CompC1OMSCMM … Go to GOV.UK and search ‘Tell HMRC about underpaid tax from previous years’ then follow the instructions. Or call us on 0300 123 0998 and quote the reference number at the top of this letter.”

ICAEW: HMRC letter CompC1OMSCMM, as published with its tax news item · checked 14 October 2026

HMRC's letter CompC1OMSCMM says a reader with no income to declare can call 0300 123 0998 or email [email protected].

“CompC1OMSCMM … If you don’t have income to declare … call us on 0300 123 0998 … email us at [email protected]”

ICAEW: HMRC letter CompC1OMSCMM, as published with its tax news item · checked 14 October 2026

HMRC's letter CompC1OMSCMM says anyone whose health or personal circumstances make it difficult to deal with HMRC can tell HMRC, and points to GOV.UK, search “Get help from HMRC if you need extra support”.

“CompC1OMSCMM … If you have any health or personal circumstances that may make it difficult for you to deal with us, please tell us. … For more information, go to GOV.UK and search ‘Get help from HMRC if you need extra support’.”

ICAEW: HMRC letter CompC1OMSCMM, as published with its tax news item · checked 14 October 2026