Quick answer
The 2025/26 tax year runs from 6 April 2025 to 5 April 2026. You must register by 5 October 2026, file a paper return by 31 October 2026, and file online and pay any tax due by 31 January 2027.
Updated October 2026 · Figures based on 2025/26 rates
Filing your Self Assessment doesn’t have to be stressful. Let our qualified accountants handle everything — accurately and on time.
Key dates at a glance
6 April 2025: tax year begins. 5 April 2026: tax year ends. 5 October 2026: register if you are new to Self Assessment. 31 October 2026: paper return deadline. 31 January 2027: online return deadline and balancing payment. 31 July 2027: second payment on account.
Which deadline applies to you
Almost everyone files online, so 31 January 2027 is the date that matters. Paper returns are an option but the earlier deadline makes them less practical.
Want an accountant to handle this for you?
Fixed price from £199 + VAT. Done for you online by UK accountants.
Order online now See our late Self Assessment tax return service service
Planning backwards
Gather records in autumn, file well before Christmas, and aim to pay by mid-January so a bank delay does not make you late.
Don’t leave your tax return to the last minute. Avoid penalties, save time, and let an expert take care of it for you.
Frequently asked questions
When is the next Self Assessment deadline?
The next online deadline is 31 January 2027 for the 2025/26 tax year.
Do I get extra time if I file on paper?
No. Paper returns have an earlier deadline of 31 October.
Ready to file without the stress?
Fixed price from £199 + VAT. Done for you online by UK accountants.
Order online now See our late Self Assessment tax return service service
