Three Self Assessment dates for 2025/26, and new tools to check yours

If you file a paper tax return, HMRC must receive your 2025/26 return by 31 October 2026. Online, you have until 31 January 2027, and any tax owed must be paid by the same day. Between them sits a date that is easy to miss: file online by 30 December 2026 and, where eligible, you can ask for the bill to be collected through your tax code.

The Autumn Budget on 28 October 2026 may change figures for later years. For 2025/26, filing earlier keeps more options open.

A hypothetical example

Sam is employed through PAYE and has a little rental income, so owes some tax for 2025/26.

• On paper: the return must reach HMRC by 31 October 2026.
• Online by 30 December 2026: where eligible, Sam can ask for the tax to come through the tax code instead of in one payment.
• Online in mid-January: the return is on time if HMRC has it by 31 January 2027, and the whole bill is due that day.

The tax is the same each time. What changes is the deadline Sam works to, and how the bill is paid.

What the new website does

We built the new website around three questions. Every tool is open to anyone in the UK, client or not, with no sign-up.

Which dates apply to me?

The tax calendar lists the 2026/27 dates for Self Assessment, PAYE, VAT and the Construction Industry Scheme. Filter by who you are (individuals and the self-employed, landlords, employers or CIS contractors) and download your dates into your own calendar.

What are the rates?

Tax rates and allowances puts the 2026/27 figures for income tax, National Insurance, VAT and more on one page, each linked to its official source. After 28 October 2026, check the source date on any figure before relying on it.

Roughly what will I owe?

The calculators cover take-home pay, VAT, CIS deductions, company car benefit and business planning, and each sets out its assumptions. Two go further:

• the rental income tax calculator estimates the tax on rental profit, which is where Sam would start;
• the payments on account calculator shows your 31 January and 31 July Self Assessment payments, and whether it may be worth asking HMRC to reduce them.

Need a form rather than a figure? Forms and official services points to the current HMRC or Companies House form or online service. Our factsheets explain topics from VAT registration to Making Tax Digital, with their official sources.

When the answer depends on your figures

The tools give general figures and cannot see your records, so your own answer may differ. If a date or a number will affect a decision, ring us on 0113 460 1786 or send us a message. Tell us which of the three dates you are aiming for and we will start from there.

This article provides general information, not personal tax, legal or financial advice. Rules and guidance can change; check the official sources and seek advice for your circumstances.