Fill and sign Form SA100 online
The paper Self Assessment tax return for the 2025 to 2026 tax year (6 April 2025 to 5 April 2026).
Form SA100 at a glance
- Official name
- SA100 Tax Return (2026)
- Issued by
- HMRC
- Country
- United Kingdom
- Category
- Tax
- Language
- English
- Who uses it
- Self-employed people, landlords and others who file Self Assessment on paper.
- Signature
Check with the recipient
GOV.UK does not say whether an electronic signature is accepted on the paper SA100. The form asks you to sign and date the declaration in box 22; if in doubt, sign by hand or file online instead.
- Instructions
- Official HMRC page
The SA100 is HMRC's main Self Assessment tax return, used by people who report income such as self-employment profits, rental income or untaxed income and choose to file on paper. Open the official 2026 form from GOV.UK in BunnyDoc's free Sign PDF tool straight from this page, type into its fillable fields, add your signature and date, and download it to print and post. Everything happens in your browser, so the file never leaves your device.
How to fill in and sign Form SA100
Open the 2026 form and check the tax year
Use the button on this page to open SA100-2026.pdf from GOV.UK. It covers the tax year 6 April 2025 to 5 April 2026.
Fill in your personal details (page TR 1)
Enter your date of birth, name, address, phone number and National Insurance number. Add your Unique Taxpayer Reference (UTR) where the form asks for it.
Answer the questions about supplementary pages (TR 2)
Answer Yes or No for each type of income, such as employment, self-employment, partnership, UK property, foreign income or capital gains. If you answer Yes, you also need that supplementary page.
Report income and reliefs (TR 3 to TR 5)
Enter UK interest, dividends, pensions, benefits and other income, then pension contributions, Gift Aid, Student Loan repayments and the High Income Child Benefit Charge if they apply. Use whole pounds and leave boxes that do not apply blank.
Finish the tax calculation and repayment details (TR 6 and TR 7)
Say whether you want any tax owed collected through your tax code and give bank details for a repayment. Add adviser details or other information if you need to.
Sign the declaration (TR 8) and post it to HMRC
Sign and date box 22. UK residents post the return to Self Assessment, HM Revenue and Customs, BX9 1AS, United Kingdom. It must reach HMRC by 31 October 2026.
What you need before you start
- Your UTR and National Insurance number.
- Your P60 or P45, and records of any self-employment, rental, savings, dividend or foreign income for 6 April 2025 to 5 April 2026.
- Details of pension contributions and Gift Aid donations.
- Any supplementary pages you need, from GOV.UK.
- The SA150 notes on how to fill in the return.
Paper and online deadlines
For the 2025 to 2026 tax year, a paper return must reach HMRC by 11:59pm on 31 October 2026. An online return is due by 11:59pm on 31 January 2027, which is also the deadline to pay any tax you owe. See Self Assessment deadlines on GOV.UK.
If you miss the paper deadline, GOV.UK advises filing online instead to avoid a late filing penalty.
Common mistakes
- Using a form for the wrong tax year.
- Forgetting the supplementary pages for income you said Yes to on page TR 2.
- Writing in boxes that do not apply or striking them through. HMRC asks you to leave them blank.
- Entering pence. Figures should be in whole pounds.
- Not signing and dating the declaration in box 22.
Form SA100: frequently asked questions
When is the paper SA100 deadline?
For the 2025 to 2026 tax year, HMRC must receive a paper return by 31 October 2026. Online returns have until 31 January 2027.
Where do I send the SA100?
UK residents send it to Self Assessment, HM Revenue and Customs, BX9 1AS, United Kingdom. If you live outside the UK, GOV.UK gives the address HM Revenue and Customs, Benton Park View, Newcastle Upon Tyne, NE98 1ZZ.
Do I need supplementary pages?
Yes, if you answer Yes to a question on page TR 2, for example about self-employment or UK property income. Each supplementary page is a separate form on GOV.UK.
Can I sign the SA100 electronically?
GOV.UK does not say. The form asks you to sign and date the declaration, so the safest route for a paper return is a handwritten signature, or file online instead.
Is BunnyDoc connected to HMRC?
No. BunnyDoc is not affiliated with HMRC. We link to the official form on GOV.UK and give you a free tool to fill and sign it in your browser.
BunnyDoc is not affiliated with HMRC. Check that the recipient accepts electronic signatures.
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