Fill the SA100 Self Assessment Tax Return Online

The SA100 is the main Self Assessment tax return form issued by HM Revenue & Customs (HMRC). It is used to declare income that has not already been taxed through PAYE — for example self-employment profit, rental income, dividends, capital gains, foreign income, and pensions. The form covers a UK tax year (6 April to 5 April the following year) and may be supplemented by additional SA1xx pages depending on the types of income you have. PDF Edit lets you fill the official HMRC SA100 PDF in your browser without an account.

The SA100 is the core return; supplementary pages cover specific income types. SA101 is for additional information (lump sums, share schemes, certain reliefs); SA102 is for employment income that doesn't fit the main return; SA103 is for self-employment; SA104 is for partnership income; SA105 is for UK property and rental income; SA106 is for foreign income; SA107 is for trusts and estates; SA108 is for capital gains; and SA109 is for non-residents and dual residents. Only attach the pages that apply to you — most filers need just one or two.

The UK tax year runs 6 April to 5 April the following year, not the calendar year. The SA100 you file in 2026 covers the year ending 5 April 2026 (often called the 2025 to 2026 tax year), and reports income earned between 6 April 2025 and 5 April 2026. The previous year's SA100 covered the year ending 5 April 2025. PDF Edit loads the version of the SA100 that HMRC has currently published for the live filing window — when HMRC issues a new revision for the next tax year, we update the source automatically.

Two different deadlines apply. If you file the paper SA100, HMRC must receive it by midnight on 31 October following the end of the tax year. If you file online through HMRC's Self Assessment service, the deadline is 31 January — three months later. The tax itself, including any balancing payment and the first payment on account, is due by 31 January regardless of which route you use. PDF Edit can be used to prepare either route, but submission is always through the post or through HMRC's online service.

HMRC charges automatic penalties for late Self Assessment returns. You will receive an immediate £100 fixed penalty as soon as the deadline passes, even if you owe no tax. After three months HMRC adds £10 daily penalties (up to £900). At six months a further penalty of 5% of the tax due (or £300, whichever is greater) is added, and the same again at twelve months. Interest also runs on any unpaid tax. If you have a reasonable excuse you can appeal, but it is far cheaper to file on time — even an estimated return is better than a missed deadline.

You fill both. Every Self Assessment filer completes the main SA100, and self-employed sole traders attach the SA103 (short or full version, depending on turnover) to declare business income, expenses, and profit. The SA103 calculates your taxable self-employment profit, which is then carried over to the SA100. You also need a Unique Taxpayer Reference (UTR) — register for Self Assessment with HMRC if you don't already have one. PDF Edit publishes the SA103 separately on this site for the supplementary page.

UK landlords with rental income above £1,000 a year (the property allowance) need to file Self Assessment. You complete the main SA100 plus the SA105 supplementary page for UK property. The SA105 captures gross rents, allowable expenses (mortgage interest is now relieved as a 20% tax credit, not a deduction), and any wear-and-tear claims. If you let property abroad, use the SA106 (foreign) instead. Furnished holiday lettings have separate boxes within the SA105.

Yes. PDF Edit processes everything inside your browser — nothing is uploaded to a server. Your UTR, National Insurance number, income figures, bank account details, and any other personal information stay on your device. We have no account system and no server-side storage, so technically we have no way of seeing what you type. That matters for SA100 because it carries some of the most sensitive personal data HMRC handles.

Yes. After you have filled the form, click Save to download the completed PDF without any watermark, or use Ctrl+P (Cmd+P on a Mac) to print straight from the editor. The printed pages match HMRC's official SA100 layout, so you can sign the declaration and post the return to the address shown on the form (Self Assessment, HM Revenue and Customs, BX9 1AS, United Kingdom) by the 31 October paper deadline. Keep a copy and your supporting records for at least 22 months after the end of the tax year.

Yes. PDF Edit loads the SA100 PDF directly from HMRC's publication on gov.uk (assets.publishing.service.gov.uk). We don't recreate the form, change its layout, or alter any of the boxes — you fill exactly the document HMRC publishes for the current tax year. PDF Edit does not submit your return to HMRC; submission is done by post for the paper SA100 or through HMRC's online Self Assessment service at gov.uk/log-in-file-self-assessment-tax-return.