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Deadlines4 min read

The Self Assessment dates that actually matter

FTWritten by the Filed Tax team · Updated July 2026
The short answer

Which tax dates matter? Just four, and they're the same every year: 5 October, 31 October, 31 January and 31 July.

Why care? Miss one and it costs you money. They all follow the tax year, which runs from 6 April to 5 April.

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On this page · 3 sections
  1. The four dates to remember
  2. Don't leave registering to the last minute
  3. What Making Tax Digital changes

The four dates to remember

  • 5 October — the deadline to register for Self Assessment if you've never filed before. Tell HMRC you have income to declare, and they'll set you up.
  • 31 October — the deadline if you file a paper return. Almost nobody needs to; online gives you three more months.
  • 31 January — the big one. Your online return is due, and any tax you owe must be paid by this date too.
  • 31 July — if you make payments on account, your second instalment is due.
Filing and paying are two separate things — on the same day. 31 January is both the deadline to submit your return and to pay what you owe. It's easy to file on time but forget the payment, and that still lands you a late-payment penalty.

Don't leave registering to the last minute

Registering isn't instant. HMRC posts you a Unique Taxpayer Reference (UTR), and that can take a couple of weeks to arrive — longer in busy periods. If you only realise in January that you should have registered in October, you can be left scrambling. If in doubt, register early; there's no harm in it.

What Making Tax Digital changes

From April 2026, Making Tax Digital for Income Tax starts replacing the single annual return with quarterly updates for those above the income thresholds. If that's you, the rhythm of deadlines changes — more often, but smaller each time. We keep track of all of them for you either way.

Never miss a tax deadline again

We track every date, chase you in good time, and file it all — from £25 a month.

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Rob Webb
Written by the Filed Tax team. Every return we file is reviewed by Rob Webb, practising accountant since 2015

Rob is a Certified Xero Advisor with a BSc from the University of Salford. This guide is general information, not personal tax advice. Deadlines and rules can change — always confirm the current position on GOV.UK or ask us to check. Figures reflect the 2025/26–2026/27 position.

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