Missing a tax deadline rarely comes with a gentle reminder. HMRC applies automatic penalties and interest, and they add up quickly - often costing far more than the time it would have taken to file on time. The good news is that the UK tax calendar is predictable once you know the key dates. Here is a straightforward guide to the deadlines that matter most.

Self Assessment

If you submit a Self Assessment tax return, these are the dates that should be circled on your calendar:

  • 31 January - Online tax return due, plus your balancing payment (any tax you still owe for the previous year) and your first payment on account.
  • 31 July - Second payment on account due.
  • 31 October - Paper tax return due (most people now file online, but if you file on paper this is your deadline).

Payments on account can catch people out. They are advance payments toward your next tax bill, usually based on your previous year's tax. If your income has dropped significantly, you can apply to reduce them - but get advice first, because underpaying leads to interest charges.

VAT returns

VAT returns and the payment of any VAT owed are due one month and seven days after the end of your VAT period. If your quarter ends on 31 March, your return and payment are due by 7 May.

If you are registered for VAT, you must submit returns online and pay electronically - HMRC no longer accepts paper VAT returns. Missing a return triggers an automatic default surcharge, and repeated defaults escalate the penalty percentage.

Corporation Tax

For limited companies, Corporation Tax works slightly differently because the deadline depends on your accounting period:

  • Pay Corporation Tax - within 9 months and 1 day of the end of your accounting period.
  • File your Company Tax Return - within 12 months of the end of your accounting period.

So if your company year ends on 31 March, the tax must be paid by the following 1 January, and the return filed by the following 31 March.

PAYE and payroll

If you run payroll, PAYE and National Insurance must reach HMRC:

  • By the 22nd of the following tax month if you pay electronically (most businesses).
  • By the 19th if you pay by post.

You also have an annual deadline: your Full Payment Submission (FPS) for the final employee pay of the tax year must be submitted by 5 April, with final reports due by 19 April.

A simple way to stay ahead

The single most effective habit is to keep your records up to date throughout the year. Scrambling to find receipts and figures in January is how mistakes - and missed deadlines - happen. Set a recurring monthly reminder to reconcile your books, and schedule a review with your accountant well before any deadline so there is time to sort out issues without panic.

If you are ever unsure whether a deadline applies to you, or you think you might miss one, the best thing to do is contact HMRC or your accountant as early as possible. HMRC is generally more accommodating with taxpayers who engage early, and your accountant can often help you get back on track with minimal fuss.