HMRC letter codes · One-to-many letters
OTM000648Letter about income from online marketplace sales
Published by its source on 28 February 2025. 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
OTM000648 is the name LITRG gives to the file of this HMRC letter. The number is not printed in the letter text. The letter is headed “Please tell us about income you’ve earned from online marketplace sales”, and this published copy has placeholders in square brackets where the dates belong.
“Please tell us about income you’ve earned from online marketplace sales … What you need to do by [SEES to insert 30 days from the date of the letter]”
LITRG: copy of HMRC letter file OTM000648, published on its page · checked 14 October 2026
Information, not advice: this page reports what HMRC, GOV.UK and the bodies named publish about OTM000648. Each fact has its source and the day it was checked beside it.
What it is
The wording of the file OTM000648 is the wording of HMRC's letter CompC1OMSCMM, published by ICAEW: the LITRG copy opens with the same heading and has the same request to declare income or contact HMRC.
“Please tell us about income you’ve earned from online marketplace sales … Please declare any income or contact us.”
LITRG: copy of HMRC letter file OTM000648, published on its page · checked 14 October 2026
ICAEW's PDF of HMRC's letter CompC1OMSCMM carries the same heading and the same request as the LITRG file OTM000648, so the two pages are two copies of one letter.
“CompC1OMSCMM … Please tell us about income you’ve earned from online marketplace sales … Please declare any income or contact us.”
ICAEW: HMRC letter CompC1OMSCMM, as published with its tax news item · checked 14 October 2026
LITRG offers an example of HMRC's letter on its page and files it on its site as OTM000648.
“We have an example of the HMRC letter available to view.”
LITRG: HMRC ‘nudge’ letters: income from online marketplaces up to 5 April 2023 – what you need to do · checked 14 October 2026
HMRC's letter file OTM000648 tells the reader HMRC has information that shows they earned income from online marketplace sales up to the tax year ending 5 April 2023.
“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.”
LITRG: copy of HMRC letter file OTM000648, published on its page · checked 14 October 2026
When HMRC sends it
LITRG said, on the page that offers HMRC's letter file OTM000648, that HMRC was sending out letters to people it thought had earned income from online marketplace sales before 5 April 2023 but had not yet declared this income to HMRC.
“HM Revenue & Customs (HMRC) are sending out letters to people that they think have earned income from online marketplace sales before 5 April 2023, but who have not declared this income to HMRC yet.”
LITRG: HMRC ‘nudge’ letters: income from online marketplaces up to 5 April 2023 – what you need to do · checked 14 October 2026
What it asks
HMRC's letter file OTM000648 asks the reader to declare any income or contact HMRC.
“Please declare any income or contact us.”
LITRG: copy of HMRC letter file OTM000648, published on its page · checked 14 October 2026
Free help and HMRC contacts
HMRC's letter file OTM000648 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.
“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.”
LITRG: copy of HMRC letter file OTM000648, published on its page · checked 14 October 2026
LITRG says, on the page that offers HMRC's letter file OTM000648, that a reader on a low income who cannot afford a professional tax adviser should contact the tax charity TaxAid, who may be able to assist.
“If you are on a low income and cannot afford to pay for a professional tax adviser, you should contact the tax charity TaxAid, who may be able to assist you.”
LITRG: HMRC ‘nudge’ letters: income from online marketplaces up to 5 April 2023 – what you need to do · 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.
- LITRG: copy of HMRC letter file OTM000648, published on its page (checked 14 Oct 2026)
- ICAEW: HMRC letter CompC1OMSCMM, as published with its tax news item (checked 14 Oct 2026)
- LITRG: HMRC ‘nudge’ letters: income from online marketplaces up to 5 April 2023 – what you need to do (checked 14 Oct 2026)
- GOV.UK: Get help from HMRC if you need extra support (checked 7 Oct 2026)
- GOV.UK: Appoint someone to deal with HMRC on your behalf (checked 7 Oct 2026)
- TaxAid: About us (checked 8 Oct 2026)
- Citizens Advice: About us (checked 7 Oct 2026)