Self Assessment deadline: 31 January 2027 online, 31 October 2026 on paper

If you file on paper, your Self Assessment deadline for 2025 to 2026 is Saturday 31 October 2026, a week from today. File online and you have until 31 January 2027, which is also when any tax you owe has to be paid.

HM Revenue & Customs (HMRC) issued the reminder on 23 October 2026, 100 days out from the online deadline. It expects around 12 million people to file by then.

Not sure you need to file at all? HMRC’s checker on GOV.UK will tell you. If you no longer need to submit a return, you can tell HMRC through GOV.UK as well.

Filing early doesn’t move the payment date. What it gets you, HMRC says, is the figure in time to budget for it alongside the other costs of running the business, and a quicker refund if you’ve paid too much tax. HMRC also lists avoiding penalties among the reasons to file early, though the notice doesn’t give the amounts. If deductions were taken from your pay, see what a CIS sole trader gets back.

Already signed up to Making Tax Digital for Income Tax? You still submit this return in your usual way and pay any tax owed by 31 January 2027. Signing up doesn’t get you out of it.

Self Assessment needs its own diary entry, starting with your UTR

New to Self Assessment? Register first. HMRC sends you a Unique Taxpayer Reference, and you need it to complete and file the return, so don’t leave registering until the week you sit down to do the paperwork.

You can complete and file the return on GOV.UK, and the online form has help text on every section. HMRC says a tax agent or a voluntary organisation can help too. If an accountant handles yours, agree now when they need your records.

The reminder covers your Self Assessment return only. It doesn’t move other dates you may have as a contractor, such as your CIS monthly return deadline.

If you pay the High Income Child Benefit Charge, GOV.UK’s guidance has a catch: if you need to stay in Self Assessment for other reasons, you must pay that charge through Self Assessment rather than your tax code.

One more date. If you also have PAYE income, HMRC says you can file online before 30 December and have any tax owed collected through your tax code. The notice doesn’t say who qualifies, so check before you count on it.