SA370 Form Guide

How to Complete the SA370 Appeal Form

The SA370 is HMRC's official form for appealing Self Assessment penalties for late filing and late payment. Here's exactly what you need to fill in.

What is the SA370?

Form SA370 is the official HMRC appeal form for Self Assessment penalties. It allows you to formally challenge a penalty for late filing or late payment by stating your reasonable excuse. For partnership tax returns, use form SA371 instead.

Fields you need to complete

1. Your full name
As it appears on your tax records
2. Unique Taxpayer Reference (UTR)
10-digit number from your tax letters or Government Gateway account
3. National Insurance number
Format: QQ 12 34 56 A — found on payslips or NI letters
4. Tax year
The tax year the penalty relates to, e.g. 2024/25
5. Penalty reference number
Found at the top of your SA326D penalty notice
6. Date you filed your return
If you have now filed — include the date
7. Date you paid your tax
If applicable — for late payment penalties
8. Reasonable excuse tick box
Tick which category your excuse falls under
9. Detailed explanation
This is the most important section — explain what happened, when, and why it prevented you from meeting the deadline
10. Signature and date
You must sign and date the form

Where to send it

Post your completed SA370 form to the address on your penalty notice. The standard HMRC Self Assessment address is:

HM Revenue & Customs
Self Assessment
PO Box 4000
Cardiff
CF14 8HR

Time limit

You have 30 days from the date on your penalty notice to submit your appeal. If you are appealing late, include an explanation of why you could not appeal sooner.

Alternative: appeal online

You can also appeal online through your Government Gateway account. Log in, select "Appeal a penalty" from your Self Assessment account summary, and follow the steps. This is faster than posting the SA370.

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