Tax / The briefing

Self Assessment: the key deadlines

A little preparation makes January considerably less demanding.

By James Reed · 1 October 2026 · 4 min read

Start with registration

If you need to send a tax return for the first time, you generally need to tell HMRC by 5 October following the end of the relevant tax year. A UK tax year runs from 6 April to 5 April. Check whether you need to register rather than assuming that tax deducted through PAYE settles everything.

Know your filing and payment dates

The usual paper filing deadline is 31 October after the tax year ends. Online returns and the balancing payment are normally due by the following 31 January. If payments on account apply, the first is also normally due on 31 January and the second on 31 July.

Keep money and records aside

Gather income statements, business records and details of allowable expenses throughout the year. Payments on account are advance payments towards a future bill, so your January payment can be larger than expected. Ask for advice before reducing them: interest may arise if you reduce them too far.

General information for England and Wales, reviewed October 2026. This is not advice on your individual circumstances. Rules and guidance may change.

02 / Further reading