If you’ve ever asked yourself ‘when does the UK tax year start?’ you’re not alone. The UK tax year starts on the 6th of April and runs until the 5th of April the following year. It’s a bit of an odd timeline, but there’s a historical reason for it, involving changes to the Julian calendar.

While the origins of the financial year in the UK might be ancient, these dates are crucial for anyone paying tax, filing returns or claiming refunds. So, let’s break it all down in a simple, stress-free way.

When does the UK tax year start and end?

Understanding the tax year is essential whether you’re self-employed, employed under PAYE or running your own company. Knowing when the tax year starts and ends can help you plan ahead, file tax returns on time and make the most of your tax allowances.

Key UK tax dates

Here are some important dates to keep in mind:

  • 6th April – The tax year begins
  • 5th April – The tax year ends
  • 31st January – The deadline for filing online Self Assessment tax returns for the previous tax year
  • 5th October – Deadline to register for Self Assessment if you’ve never filed before
  • 31st July – Second payment on account deadline for those paying tax via Self Assessment

UK Tax Dates

Fancy seeing if your tax knowledge is better than the rest? We asked members of the public when the new tax year starts. Watch this quick video to see their responses.

Why is the tax year important?

Understanding UK tax year dates isn’t just for accountants and finance whizzes. It matters to everyone who earns money, whether you’re employed, self-employed or running a business. Here’s why:

Tax return deadlines

Missing deadlines can be expensive. If you need to complete a Self-Assessment tax return, you have until the 31st of January to file online. Paper tax returns (if you still fancy doing things the old-school way) need to be in by the 31st October.

Tax allowances

The tax year also determines your Personal Allowance – the amount you can earn before paying tax. For most people, that’s £12,570 (though it can change each tax year). If you’re self-employed, it’s when your business expenses, deductions and tax reliefs reset.

What is the 2025-26 personal allowance?

Tax deadlines you should know

Tax deadlines aren’t just for those who are self-employed – everyone needs to pay attention. Here’s what you need to keep in mind:

Self Assessment

If you’re self-employed, a freelancer or have income that isn’t taxed at source, you’ll need to file a Self-Assessment Tax Return. The deadline for online filing is the 31st of January, and payments are due twice a year – 31st of January and 31st of July. 

We also asked people if they knew when the Self Assessment tax deadline is – check out the video below to hear their answers:

 

PAYE (Pay As You Earn)

If you’re employed and tax is deducted from your wages through PAYE, you don’t have to file a tax return. However, it’s still worth checking if you’re owed a tax refund – especially if you’ve changed jobs, had work-related expenses or been on emergency tax. Find out what you need to know before the new tax year.

What happens if you miss the deadline?

Tax deadlines aren’t suggestions and they come with penalties if you ignore them. Here’s what can happen if you miss your Self Assessment deadline:

  • 1 day late – Automatic £100 fine, even if you don’t owe any tax
  • 3 months late – £10 per day fine (up to £900)
  • 6 months late – 5% of the tax owed (or £300, whichever is higher)
  • 12 months late – Another 5% (or £300) fine

For PAYE taxpayers, not submitting the right tax details can lead to incorrect tax codes, meaning you might be paying too much (or too little) tax. Either way, it’s best to stay on top of it.

More on tax return penalties

Tips for staying on top of the tax year

A bit of planning can save you a lot of hassle in the long run. Here are some simple ways to keep your tax affairs in check:

Set calendar reminders

Mark key dates in your diary, set phone alerts or stick a big note on your fridge – whatever helps you remember!

Keep your records organised

If you’re self-employed, keeping receipts, invoices and business expenses in one place will make life much easier when it's time to file your tax return.

What records do I need to keep?

Work with RIFT experts

Not sure if you’re due a tax refund? Let RIFT handle it. We specialise in getting people back the money they’re owed. We’ll help you maximise your refund and ensure you’re not paying more than you should.

Meet the RIFT Experts

Get your tax sorted with RIFT Refunds

The tax year might run from April to April, but don’t leave your tax affairs until the last minute. Whether you need to file a return, check if you’re due a refund or just want peace of mind, RIFT is here to help. Start your claim today with our tax rebate calculator and let's make sure you’re on track!