Key tax dates you need to know if you are self-employed

Why self-employed tax dates matter  

You set up your business, you’re working hard gaining customers, finding reliable suppliers, maybe employing your first members of staff. Fees are coming in and you are building a good reputation – your confidence is growing. But failing to get to grips with your tax and accounting could ruin all your hard work, because you could end up with: 

• Penalties and interest to pay on top of your tax bill 
• More attention from HMRC, so more of your time taken up corresponding with them or compiling evidence  
• Cashflow problems if you aren’t prepared for deadlines and haven’t put the money aside to pay  
• Chasing your tail and paying more than you need to 

If you plan your tax and tax reporting properly, you can avoid fines, make the most of tax reliefs and allowances and keep more of your hard-earned cash. 

Your self-assessment timeline at a glance  

Summary of key dates 

31st January	Deadline to submit self-assessment tax return online
	Pay balance of tax for prior tax year
	Pay first payment on account, if applicable
5th April	End of tax year
6th April	Start of tax year
31st July	Pay second payment on account, if applicable
5th October	Notify HMRC if you need to register for self-assessment for a new business
31st October	Deadline to submit tax return on paper
30th December	Deadline to submit tax return if tax is to be collected by PAYE tax code

31st January 

This is the deadline for filing self-assessment tax returns as well as being the date that self assessment income tax must be paid. If you are required to make payments on account, as well as paying the balance of tax for the previous tax year you will also be required to make your first payment on account for the forthcoming tax year. Details on paying your tax can be found here. 

5th April 

This is the end of the tax year and is an important date for tax planning. Tax planning means looking at your finances ahead of the end of the tax year and making decisions that may affect your tax liability. Click here to learn about eight ways you can save on tax. 

6th April 

This is the start of the new tax year and introduces new tax and National Insurance Contributions (NICs) rates and thresholds to be aware of. For tips for the start of the 2026/27 tax year click here.

31st July 

If you are required to make payments on account, the second payment is due by 31st July. 

5th October 

For new businesses and individuals, you have until 5th October following the tax year in which you began trading to register yourself for self-assessment with HMRC. For instance, if you start trading on 1st July 2026, you have until 5th October 2027 to register.  

31st October 

For those submitting a tax return on paper, the deadline for submission is 31st October (not 31st January). 

30th December 

For those wanting to pay their underpaid tax through their tax code, the deadline for submission is 30th December. If the tax return is filed after this date, the tax will have to be paid outside the PAYE system by 31st January. 

What happens if you miss a deadline?  

If you miss a filing deadline or pay your tax late, it will result in penalties.  

Penalties 

For the 2025/26 and 2026/27 tax years, penalties for late filing of tax returns are automatic and time based, beginning with a £100 penalty for filing one day late.  

Penalties for late payment of tax are based on a percentage of the unpaid tax and add up if tax remains unpaid are set intervals, beginning with 30 days after the payment deadline. 

From 2027/28, the Government has announced that late filing penalties for self-assessment tax returns will move to a points based model in line with Making Tax Digital for Income Tax. 

When do I need to join Making Tax Digital for income tax? 

If you are: 

• sole trader, or  
• a self-employed landlord 

and in your 2024/25 tax return you declared qualifying income of £50,000 or more, you must join Making Tax Digital for income tax from 6th April 2026. For help on calculating your qualifying income, see our article here. 

Those with £30,000 or more qualifying income must join by 6th April 2027 and for £20,000 or more, the joining date is 6th April 2028. 

Speak to your accountant to find out which digital bookkeeping solution would meet your business’ needs to be Making Tax Digital for income tax compliant. 

Last updated: 30th March 2026