HMRC letter codes · Self Assessment (SA)
SA303Claim to reduce payments on account
Last reviewed 14 October 2026 · How Tax Letters checks its facts
In short
GOV.UK says to use the SA303 form to apply to reduce your Self Assessment payments on account.
“Use the SA303 form to apply to reduce your Self Assessment payments on account.”
GOV.UK: Claim to reduce payments on account · checked 14 October 2026
Information, not advice: this page reports what HMRC, GOV.UK and the bodies named publish about SA303. Each fact has its source and the day it was checked beside it.
What it is
GOV.UK's guide to the Self Assessment tax bill describes payments on account, which is what the SA303 claim is about, as payments towards your next bill.
“payments on account (payments towards your next bill)”
GOV.UK: Understand your Self Assessment tax bill · checked 14 October 2026
When HMRC sends it
HMRC's Self Assessment manual forms index describes SA303 as the Claim to Reduce Payments on Account. It says these forms were previously sent out with December statements and were last sent in December 2014.
“Claim to Reduce Payments on Account. (These forms were previously sent out with December statements but were last sent in December 2014)”
GOV.UK: HMRC Self Assessment Manual, SAM002 Forms Index · checked 14 October 2026
Time limits and rules
GOV.UK's page on form SA303 says you can apply to reduce the amounts you have been asked to pay if your business profits or other income goes down, the tax relief you are entitled to goes up, or tax deducted at source is more than the previous tax year.
“You can apply to reduce the amounts you’ve been asked to pay if: … your business profits or other income goes down … the tax relief you are entitled to goes up … tax deducted at source is more than the previous tax year … Fill in form SA303.”
GOV.UK: Claim to reduce payments on account · checked 14 October 2026
GOV.UK says, on the page that names form SA303, that you must claim by 31 January after the end of the tax year. Its example is 31 January 2025 for the year 2023 to 2024.
“You must claim by 31 January after the end of the tax year. For example by 31 January 2025 for the year 2023 to 2024. … Fill in form SA303.”
GOV.UK: Claim to reduce payments on account · checked 14 October 2026
How to send it or apply
GOV.UK says that if you are unable to apply online you can fill in form SA303 and print and post it to HMRC.
“If you are unable to apply online … Fill in form SA303. Print and post it to HMRC.”
GOV.UK: Claim to reduce payments on account · checked 14 October 2026
GOV.UK says that to apply to reduce payments on account you can use the online service, or fill in the postal form SA303 on screen, print it and post it to HMRC.
“To apply either: use the online service fill in the postal form on screen, print it and post it to HMRC … Fill in form SA303.”
GOV.UK: Claim to reduce payments on account · checked 14 October 2026
Free help and HMRC contacts
For Self Assessment queries about returns, payments, replacements or notices, GOV.UK's general enquiries page gives the number 0300 200 3310 and links to information about call charges. The page does not name SA303.
“Call HMRC if you have a query about: … your Self Assessment returns, payments, replacements or notices … Telephone: 0300 200 3310 … Find out about call charges”
GOV.UK: Self Assessment: general enquiries · 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: Claim to reduce payments on account (checked 14 Oct 2026)
- GOV.UK: Understand your Self Assessment tax bill (checked 14 Oct 2026)
- GOV.UK: HMRC Self Assessment Manual, SAM002 Forms Index (checked 14 Oct 2026)
- GOV.UK: Self Assessment: general enquiries (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)