Tax year dates for small businesses – important dates to remember

Getting to grips with the UK tax year is an important step for any small business owner. While it may seem like there’s a lot to learn, noting down these key tax year dates will help you keep on top of your financial admin. 

We cover key dates for filing and paying tax for 2024-25, along with important dates for 2025-26 when Making Tax Digital comes in for more taxpayers. 

This guide covers: 

Key dates in the UK tax year

Keep reading for a rundown of the tax year dates you need to know. Whether you’re looking to avoid penalties or interest charges, or just want to make informed decisions about your finances, knowing these dates can help.

But it’s not just tax dates you need to be aware of. Make sure you know these other key dates for small businesses to plan for the upcoming year.

April 2025: current UK tax year started

• 5 April: the end of the 2024-25 tax year
• 6 April: the beginning of the 2025-26 tax year

July 2025

• 6 July: P11D forms are due on this day each year – you’ll need to submit this if you offer employee benefits like company cars or season ticket loans
• 31 July: your second Self Assessment payment on account for the 2024-25 tax year is due

September 2025

15 September: this day marks Pension Awareness Day, making it a perfect time to start thinking about setting up a self-employed pension

October 2025

• 5 October: potentially one of the most important tax year dates for the newly self-employed, this is the date to register for Self Assessment – following the end of the tax year you became self-employed
• 31 October: if you’re submitting your tax return by post, this is the deadline for submitting your Self Assessment for the previous tax year
• TBC: the government’s next Autumn Budget will likely take place at the end of October or the start of November – and is a key date for small business owners to remember

January 2026

• 31 January: online Self Assessments are due by this date – but you can submit them earlier if you wish to. Make sure you keep accurate tax records throughout the year to help avoid a last-minute panic
• 31 January: your first payment on account for the 2025-26 tax year is due on this date
• 31 January: if you’ve sold or disposed of any business assets, then you’ll need to pay capital gains tax by this date
• 31 January: this is the deadline for paying your Self Assessment tax return – even if you’ve submitted it earlier in the tax year – so don’t forget

March 2026

• TBC: the government’s Spring Budget is set to take place in March, which could bring major changes which affect small businesses

April 2026

• Making Tax Digital for income tax starts for sole traders and landlords with income over £50,000
• 5 April: the end of the 2025-26 tax year
• 6 April: the beginning of the 2026-27 tax year
• 19 April: deadline for PAYE submissions from the previous tax year (2025-26)
• 19 April: deadline for the final payments made by post for 2025-26 PAYE tax and Class 1 National Insurance contributions (NICs)
• 22 April: deadline for the final payments made electronically for 2025-26 PAYE tax and Class 1 NICs
• 30 April: the date daily penalties start for those who haven’t filed their Self Assessment (due 31 January)

May 2026 

• 31 May: deadline for issuing your employees with a P60 form – summarising their total pay and deductions for the previous tax year

Preparing for the UK tax year dates

Now that you know the key tax year dates for the upcoming year, there are a few ways to help prepare:

• add these tax year dates to your calendar
• consider setting up reminders in advance to give yourself time
• familiarise yourself with the HMRC app – spend some time getting to know where everything is so there are no holdups as tax deadlines approach
• don’t wait until the end of the tax year to scramble for receipts and invoices – keep track of your income and expenses throughout the year
• check which self-employed expenses are tax deductible when saving your receipts

Recent and upcoming changes to the rules 

• April 2025 saw National Insurance (NI) contributions increase by 1.2 per cent to 15 per cent, and the threshold for paying NI on an employee’s salary reduced from £9,100 to £5,000
• April 2025 also saw changes to business rates: the small business multiplier was frozen at 49.9p for 2025-26, while the standard multiplier increased to 55.5p
• Making Tax Digital comes in for more people from April 2026, changing how you’ll file and pay your income tax
• UK personal allowance frozen at £12,570 until April 2026

FAQ: some common questions

Do the dates of the tax year ever change?

While the tax year begins on the 6 April each year and doesn’t change, specific dates within the tax year could change.

Make sure you stay informed about any updates to tax laws, regulations, and deadlines within the tax year. The Autumn and Spring budgets often reveal upcoming changes. You can also follow our social channels and sign up for our newsletter to stay in the loop.

What’s the difference between the tax and the financial year?

While the terms are often used interchangeably, there’s a slight difference between tax year and financial year. The dates of the tax year are set by the UK government, while a company’s financial year is chosen by the company.

Can I claim tax relief for expenses incurred outside of the tax year?

You can generally only claim tax relief for expenses within the current tax year. However, there are exceptions to this rule – such as if you use accrual accounting. Make sure to speak with an accountant if you’re unsure of the exceptions.

What is the 183 day rule in the UK?

The 183 day rule affects people who live outside of the UK but still visit it more than 183 days in a year. If you visit more than this, you’ll need to pay tax in the UK.