Your Self Assessment, drafted while you sleep.

Every figure traces to a source document or bank transaction, and nothing submits itself — you review the full computation and approve before it's sent to HMRC.

Yes. The draft shows every box on every page you need, exactly as HMRC will receive it, with the source behind each figure alongside it.

Yes — ac-co is HMRC-recognised software for Self Assessment, filing through the official API. See HMRC's own list of recognised suppliers, linked above.

The draft still builds from your bank and documents in minutes, not days. Start now and you can still review and file before the 31 January deadline.

Invite them into the same draft to review before you file — or use ac-co for the parts they don't need to see, like the running SA302 estimate.

Online tax returns for the 2025/26 tax year must be submitted and any tax owed must be paid by midnight on 31 January 2027. If you file on paper, the deadline is 31 October 2026. If you need to register for Self Assessment for the first time, you must register by 5 October 2026.

Pay any tax owed for 2025/26 by 11:59pm on 31 January 2027, the same day as the online filing deadline. If HMRC asks for payments on account, the first towards 2026/27 is also due on 31 January 2027 and the second on 31 July 2027. Paying late triggers penalties and interest.

Payments on account are two advance payments towards your next Self Assessment bill, due on 31 January and 31 July. Each is half of last year's bill. You do not need to make them if last year's bill was under £1,000, or if more than 80% of it was already paid through your tax code or at source.

If you have not filed a return before, or registered earlier but did not need to file for 2024/25, you must tell HMRC by 5 October 2026 that you need to file for 2025/26. Register after that date and you could get a penalty. You still have to pay any tax by 31 January 2027.

Yes, if you owe less than £3,000, you already pay tax through PAYE (for example as an employee or on a company pension) and you file your online return by 30 December 2026. Miss that date and you will need to pay another way, by 31 January 2027.

You get an automatic £100 penalty the day after the deadline, even if you owe no tax. After 3 months it adds £10 a day, up to £900. At 6 months and again at 12 months there is a further penalty of 5% of the tax due or £300, whichever is greater.

HMRC charges interest on any tax paid after 31 January 2027, plus late payment penalties of 5% of the tax still unpaid at 30 days, 6 months and 12 months after the deadline. Filing late and paying late are separate penalties, so a late return with a late payment can attract both.

Making Tax Digital for Income Tax applies to self-employed people and landlords whose qualifying income is above a threshold. The threshold is £50,000 (2024/25 income) from 6 April 2026, £30,000 (2025/26 income) from 6 April 2027 and £20,000 (2026/27 income) from 6 April 2028. HMRC writes to those who must join.

Once you are in Making Tax Digital for Income Tax, send quarterly updates by 7 August, 7 November, 7 February and 7 May. They cover the periods to 5 July, 5 October, 5 January and 5 April, or the calendar-month equivalents. HMRC will not apply late-update penalty points for the 2026/27 tax year.

The 2026/27 tax year ends on 5 April 2027. Online returns and the tax owed are due by 31 January 2028, and paper returns by 31 October 2027. If you are new to Self Assessment, you must register by 5 October 2027.