HMRC letter codes · Debt and payment letters (IDMS)
OCA43Unpaid Income Tax
Last reviewed 14 October 2026 · How Tax Letters checks its facts
In short
GOV.UK lists OCA43 as an HMRC letter about unpaid Income Tax.
“Letter OCA43 … charged with unpaid Income Tax”
GOV.UK: Check if a QR code on a letter you’ve received from HMRC is genuine · checked 14 October 2026
Information, not advice: this page reports what HMRC, GOV.UK and the bodies named publish about OCA43. Each fact has its source and the day it was checked beside it.
What it is
GOV.UK lists OCA43 among the HMRC letters that may carry a QR code you can scan for further information or help.
“Letters and leaflets from HMRC may contain a QR code which you can scan for further information or help. … Letter OCA43”
GOV.UK: Check if a QR code on a letter you’ve received from HMRC is genuine · checked 14 October 2026
When HMRC sends it
GOV.UK says you may receive an OCA43 letter if you have been charged with unpaid Income Tax.
“Letter OCA43 … You may receive a letter if you have been charged with unpaid Income Tax.”
GOV.UK: Check if a QR code on a letter you’ve received from HMRC is genuine · checked 14 October 2026
Free help and HMRC contacts
GOV.UK says the QR code on letter OCA43 takes you to its guidance on paying your Self Assessment tax bill.
“Letter OCA43 … The QR code on the letter takes you to our guidance on paying your Self Assessment tax bill”
GOV.UK: Check if a QR code on a letter you’ve received from HMRC is genuine · checked 14 October 2026
GOV.UK’s page on paying a Self Assessment tax bill, which the OCA43 QR code leads to, says you can get help if you cannot pay your tax bill on time.
“You can get help if you cannot pay your tax bill on time.”
GOV.UK: Pay your Self Assessment tax bill · 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.
- GOV.UK: Check if a QR code on a letter you’ve received from HMRC is genuine (checked 14 Oct 2026)
- GOV.UK: Pay your Self Assessment tax bill (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)