The Ultimate UK Tax Dates Guide for Self-Employed & Small Business Owners (2025/26)
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Running your own business is incredibly rewarding, but let’s be honest: keeping on top of HMRC deadlines can feel a little overwhelming. Miss a date, and you could face automatic fines, interest charges, or even an investigation from HMRC. Stay on top of them, and you keep more of your hard-earned money where it belongs: in your pocket.
Whether you’re a freelance graphic designer, a self-employed plumber, a consultant, or running a growing limited company, this guide is your go-to resource for every key UK tax deadline you need to know. We’ve broken everything down in plain English, with no jargon and no confusion, so you can plan ahead with confidence.
đź“…Â Not Sure Where to Start? Book a Free Consultation Today. Speak with one of our friendly tax experts at AM Accountex Ltd, completely free and with no obligation. Call us on +44 744 360 9141 or email info@amaccountex.co.uk and we will make sure you never miss another HMRC deadline. |
Why UK Tax Deadlines Matter More Than You Think
Many self-employed people and small business owners only think about tax when a deadline is looming, and by then it can be too late to plan properly. HMRC operates a strict penalties regime: miss the Self Assessment deadline by even one day and you’ll receive an automatic ÂŁ100 fine. Leave it longer, and those fines compound quickly.
But staying ahead of your tax dates isn’t just about avoiding penalties. It’s about cash flow planning, avoiding nasty surprises, and running a business that feels in control. Here’s everything you need to know.
First Things First: Understanding the UK Tax Year
The UK tax year runs from 6 April to 5 April the following year. This is different from the calendar year, which catches a lot of new business owners off guard. For example, the 2025/26 tax year runs from 6 April 2025 to 5 April 2026.
All income, expenses, and tax calculations are based on this period. It is also the basis for your Self Assessment tax return, which covers everything you earned during that tax year.
💡 Quick Tip: Mark 6 April in Your Calendar Every Year The start of a new tax year is a great moment to review your record-keeping, check your National Insurance contributions, and confirm your HMRC online account is up to date. |
Self Assessment Tax Return Deadlines
The Self Assessment tax return is the most important deadline for self-employed individuals and small business owners. It tells HMRC about your income, expenses, and how much tax you owe for the previous tax year.
Who Needs to Complete a Self Assessment?
According to HMRC, you’ll need to complete a Self Assessment tax return if you:
- Were self-employed as a sole trader and earned more than ÂŁ1,000
- Were a partner in a business partnership
- Had income from renting out property
- Earned more than ÂŁ100,000 in a tax year
- Had untaxed income (such as savings interest or dividends)
- Received income from abroad
- Claimed Child Benefit and you or your partner earns over ÂŁ50,000 (High Income Child Benefit Charge)
31 October: Paper Self Assessment Deadline
Deadline: 31 October (for the previous tax year)
If you prefer to submit a paper tax return rather than filing online, you must do so by 31 October. For the 2025/26 tax year, this means your paper return must reach HMRC by 31 October 2026.
Paper returns are becoming increasingly rare, as HMRC strongly encourages online filing. They remain an option, particularly for those without internet access or for more complex cases.
⚠️ Miss the Paper Deadline? Filing your paper return after 31 October means HMRC will treat it as a late online return, and you’ll face the same online deadline of 31 January. Critically, if you miss both, automatic penalties begin immediately. |
31 January: Online Self Assessment Deadline
Deadline: 31 January (for the previous tax year; for example, 31 January 2027 for the 2025/26 tax year)
This is the big one. Every year, millions of UK self-employed people rush to file their online tax return before midnight on 31 January. Do not leave it until the last minute, as filing in a hurry increases the risk of errors and missed deductions.
On the same day, you must also pay any tax you owe for the previous year, plus your first Payment on Account for the current year (more on this below).
đź’ĽÂ Sarah, Freelance Graphic Designer, London Sarah earns ÂŁ45,000 a year from various clients. She submits her Self Assessment online by 20 January each year, giving herself time to double-check her expenses. By filing early, she knows her tax bill well in advance and can budget accordingly, avoiding any last-minute panic. |
Penalties for Missing the Self Assessment Deadline
HMRC’s penalties for late Self Assessment are structured and escalate quickly:
- 1 day late: ÂŁ100 automatic penalty (even if you owe no tax)
- 3 months late: Additional ÂŁ10 per day, up to 90 days (ÂŁ900 maximum)
- 6 months late: A further penalty of 5% of the tax owed, or ÂŁ300, whichever is greater
- 12 months late: Another 5% or ÂŁ300 charge
- Additionally, interest accrues on any unpaid tax from the payment deadline
⚠️ Important: Penalties Apply Even If You Owe Nothing Many people assume that if they don’t owe any tax, there’s no rush to file. This is incorrect. The ÂŁ100 penalty for late filing applies regardless of whether any tax is due. Always file on time. |
Payments on Account: What Are They and When Are They Due?
Payments on Account are advance payments towards your next year’s tax bill. They catch a lot of new self-employed people completely off guard, so let us break them down clearly.
If your Self Assessment tax bill is more than ÂŁ1,000 (and less than 80% of your tax was deducted at source), HMRC will ask you to make two Payments on Account each year. These are essentially prepayments of your expected tax bill for the following year, based on what you owed in the current year.
31 January: First Payment on Account
Due on the same day as your Self Assessment tax return: 31 January. This is half of your previous year’s tax bill paid in advance towards the current year.
31 July: Second Payment on Account
The second instalment is due on 31 July, right in the middle of summer. This payment often surprises people who’ve just finished their January payment and feel like they’ve dealt with tax for the year. Planning for this date is essential for cash flow.
🔧 Mark, Self-Employed Electrician, Manchester Mark’s tax bill for 2024/25 was ÂŁ4,000. This means he also had to make two Payments on Account of ÂŁ2,000 each, one in January 2026 and one in July 2026, towards his 2025/26 bill. In total, Mark paid ÂŁ8,000 in one tax year. By setting aside money monthly, he avoids the shock. |
💡 Top Tip: Use a ‘Tax Pot’ Savings Account Set aside 20–30% of every payment you receive into a separate savings account. This way, when tax deadlines arrive, the money is already there. No stress, no scrambling. |
Registering for Self Assessment: The 5 October Deadline
Deadline: 5 October (following the end of the tax year in which you became self-employed)
If you started working for yourself during the 2025/26 tax year (6 April 2025 to 5 April 2026), you must register with HMRC for Self Assessment by 5 October 2026. This tells HMRC you need to file a tax return.
Registering is straightforward and can be done online via the HMRC website. Once registered, HMRC will send you a Unique Taxpayer Reference (UTR) number, which you’ll need to file your return.
🧑‍💻 Priya, IT Consultant, Birmingham Priya left her full-time job in June 2025 and went freelance. She registered for Self Assessment through HMRC’s website in September 2025, well before the 5 October deadline. Her UTR arrived within two weeks, giving her plenty of time to prepare her first tax return. |
⚠️ Don’t Assume HMRC Will Contact You HMRC will not automatically know you’ve become self-employed. It is your legal responsibility to register. Failing to do so can result in penalties and backdated tax demands. |
VAT Registration and Deadline Dates
VAT (Value Added Tax) is charged at 20% on most goods and services. As a business owner, you need to register for VAT if your taxable turnover exceeds the VAT threshold, which is currently ÂŁ90,000 (as of 2025/26).
Ongoing VAT Threshold Monitoring
You must monitor your rolling 12-month turnover continuously. If it exceeds ÂŁ90,000, you must register for VAT within 30 days of the end of the month in which you crossed the threshold. HMRC will backdate your registration if you fail to register on time, meaning you will owe VAT on sales you have already made.
VAT Return Deadlines
Once registered, most businesses file VAT returns quarterly, with payment due one calendar month and seven days after the end of each VAT quarter. For example:
- Quarter ending 31 March → Return and payment due 7 May
- Quarter ending 30 June → Return and payment due 7 August
- Quarter ending 30 September → Return and payment due 7 November
- Quarter ending 31 December → Return and payment due 7 February
💡 Making Tax Digital for VAT All VAT-registered businesses are now required to keep digital records and submit VAT returns using compatible software under HMRC’s Making Tax Digital (MTD) scheme. Check HMRC’s approved software list to ensure you’re compliant. |
National Insurance Contributions for the Self-Employed
As a self-employed person, you pay two types of National Insurance Contributions (NICs), and understanding when they are due is an important part of managing your tax obligations.
Class 2 National Insurance
Class 2 NICs are no longer collected separately. They are now included in your Self Assessment tax return and collected alongside your income tax payment. If your profits exceed the Small Profits Threshold (ÂŁ6,845 for 2025/26), Class 2 NICs will be included automatically in your January bill.
Class 4 National Insurance
Class 4 NICs are calculated as a percentage of your profits and are also paid through Self Assessment alongside your income tax in January and July.
- 6% on profits between ÂŁ12,570 and ÂŁ50,270
- 2% on profits above ÂŁ50,270
PAYE and Employer Deadlines (If You Have Staff)
If you employ people, even just one person, you take on additional HMRC obligations as an employer. These are separate from your own personal tax deadlines.
Monthly PAYE Payments
Most employers must pay PAYE (income tax and NICs deducted from employees’ wages) to HMRC by the 19th of each month (or 22nd if paying electronically). Payments must cover the previous month’s payroll.
Annual PAYE Deadlines
- 5 April: Deadline for employees to receive their P60 (summary of pay and tax for the year)
- 6 July: P11D forms must be submitted (reporting benefits and expenses for employees)
- 19 July: Class 1A National Insurance on benefits in kind must be paid
🏪 James, Small Café Owner, Bristol James employs three part-time staff. He uses payroll software to calculate PAYE each month and ensures payments reach HMRC by the 22nd. Each April, he prepares P60s for all staff and files his P11D by 6 July. Staying organised month-by-month means he never faces unexpected employer penalties. |
Corporation Tax Deadlines for Limited Companies
If you operate as a limited company, you’ll pay Corporation Tax rather than income tax on your business profits. The current main rate of Corporation Tax is 25% (for profits over ÂŁ250,000), with a Small Profits Rate of 19% for profits under ÂŁ50,000.
9 Months and 1 Day After Year End
Corporation Tax must be paid 9 months and 1 day after the end of your accounting period. So if your company’s year end is 31 March, your Corporation Tax payment is due by 1 January of the following year.
12 Months After Year End: Company Tax Return (CT600)
Your Company Tax Return (the CT600 form) must be filed with HMRC within 12 months of your accounting period end. Please note that the payment is due before the return, which is something many company directors get the wrong way round.
⚠️ Note: The Payment Comes Before the Return Corporation Tax is due 9 months and 1 day after year end, but the CT600 return is due 12 months after year end. You must pay before you file, so plan your cashflow accordingly. |
UK Tax Calendar: Key Dates at a Glance
Use this table as your annual reference guide. We recommend bookmarking this page and setting calendar reminders for each date relevant to your business.
Date | Deadline | Who It Applies To | Penalty for Missing |
5 April | End of tax year | Everyone | N/A |
5 April | Last day: ISA contributions & pension topping up | Everyone | Lose annual allowance |
6 April | New tax year begins | Everyone | N/A |
31 July | Second Payment on Account due | Self-employed | Interest on late payment |
5 October | Register for Self Assessment (new) | New self-employed | Potential penalty |
31 October | Paper Self Assessment deadline | Self-employed | ÂŁ100 automatic fine |
19 October | PAYE quarterly payment (postal) | Employers | Surcharges apply |
1 November | Corporation Tax payment (year ending 31 Jan) | Ltd companies | Interest charges |
30 December | Online SA to collect via PAYE | Employees with SA | Miss this = lump sum |
31 January | Online Self Assessment deadline | Self-employed | ÂŁ100+ fines & interest |
31 January | First Payment on Account due | Self-employed | Interest on late payment |
31 January | Capital Gains Tax (on property) | Property sellers | Surcharges & interest |
5 April | VAT registration if threshold exceeded | VAT traders | Backdated VAT liability |
💡 Set Reminders Now Take five minutes right now to add these dates to your phone or calendar. Set a reminder two weeks before each deadline so you have time to prepare rather than simply react. |
📞 Worried About Missing a Deadline? We Can Help. The team at AM Accountex Ltd works with hundreds of UK self-employed business owners. Book your free, no-obligation consultation today and get a personalised tax timeline for your business. Call +44 744 360 9141 or email info@amaccountex.co.uk. |
7 Practical Tips to Never Miss a UK Tax Deadline Again
1. Register for HMRC’s Online Account Early
If you haven’t already, register for an HMRC online account on HMRC’s website. This is where you’ll file your Self Assessment, check your tax position, and manage your payments. The verification process can take up to 10 working days, so don’t leave it until deadline week.
2. Keep Digital Records All Year Round
Under Making Tax Digital, HMRC is moving towards mandatory digital record-keeping for all businesses. Start using HMRC-compatible accounting software from day one. It makes preparing your tax return dramatically faster and more accurate.
3. Set Up a Dedicated Business Bank Account
Mixing personal and business finances is one of the most common mistakes self-employed people make. A separate business account makes tracking income and expenses much simpler, and it will save you hours when it comes to filing your return.
4. File Your Self Assessment Early
You can file your Self Assessment as soon as the tax year ends on 5 April. Many accountants recommend filing in the summer, as this gives you several months to understand your tax bill, plan your Payments on Account, and spread the financial impact. You don’t have to pay the tax until 31 January even if you file early.
5. Set Up a Budget Payment Plan
HMRC offers a Budget Payment Plan that allows you to make regular weekly or monthly payments in advance of your Self Assessment bill. This can smooth out the cash flow impact of the January and July lump-sum payments.
6. Use HMRC’s Online Notification Service
HMRC will send reminders to your online account and registered email address as deadlines approach. Make sure your contact details on your HMRC account are up to date, as these reminders are a valuable safety net.
7. Work With a Qualified Accountant or Tax Adviser
A good accountant does not simply file your return. They actively help you plan your tax position, ensure you are claiming all allowable expenses, and keep you on top of every relevant deadline. For most small business owners, the cost of professional advice is far outweighed by the money saved and the stress avoided. AM Accountex Ltd specialises in exactly this, supporting UK self-employed individuals and small business owners with friendly, expert tax advice. Get in touch on +44 744 360 9141 or info@amaccountex.co.uk.
Common Tax Deadline Mistakes (And How to Avoid Them)
- Leaving it to the last minute: The HMRC online portal often experiences high traffic around 31 January. File early to avoid technical issues.
- Forgetting Payments on Account: Many self-employed people are blindsided by the July payment. Budget for it from day one.
- Not registering for Self Assessment: HMRC will not chase you. The responsibility is yours. Register by 5 October.
- Missing the VAT threshold: Monitor your turnover monthly. Crossing ÂŁ90,000 carries serious consequences if you fail to register.
- Assuming no tax means no return: Even if you owe nothing, a late return still incurs a ÂŁ100 fine.
- Poor record-keeping: HMRC can investigate returns going back up to 20 years in cases of deliberate error. Keep records for at least 5 years.
Frequently Asked Questions About UK Tax Deadlines
What happens if I can't pay my tax bill on time?
Contact HMRC as soon as possible. They offer a Time to Pay arrangement, which lets you spread your tax bill into manageable monthly instalments. This must be arranged before or on the deadline, not after penalties have been applied. HMRC is generally more sympathetic if you reach out proactively.
Can I get an extension on my Self Assessment deadline?
In most cases, no. HMRC does not routinely grant extensions. However, if you have a genuine reason for being unable to file, such as a serious illness or a technical failure on HMRC’s systems, you may be able to appeal a penalty. Evidence will be required.
Do I need to file a Self Assessment if I'm employed but also have freelance income?
Yes. If you earn more than ÂŁ1,000 from self-employment in a tax year (even alongside your regular employment), you must register for Self Assessment and declare that income. Your employer’s PAYE will not cover your freelance earnings.
What records does HMRC require me to keep?
Self-employed individuals must keep records of all business income and expenses for at least 5 years after the 31 January submission deadline of the relevant tax year. For limited companies, records must typically be kept for 6 years. Digital records are strongly encouraged.
When does the 2026/27 tax year begin?
The 2026/27 tax year begins on 6 April 2026 and ends on 5 April 2027. All income and expenses within this period will form the basis of the tax return due by 31 January 2028.
Ready to Take Control of Your Tax Deadlines?
Understanding your UK tax obligations as a self-employed person or small business owner can feel complex, but it does not have to be. The key is simply knowing your dates, planning ahead, and getting the right support in place before you need it.
At AM Accountex Ltd, we work with sole traders, freelancers, consultants, tradespeople, and limited company directors across the UK, helping them stay compliant, claim every allowable deduction, and never miss a deadline. Our team is friendly, approachable, and speaks plain English (not accountant-speak). You can find us at 95 Mortimer Street, London W1W 7GB.
🎯 Book Your Free Consultation Today: No Jargon, No Obligation. Whether you’re just starting out or you’ve been in business for years, the AM Accountex Ltd team is ready to help. Get in touch today: call +44 744 360 9141, email info@amaccountex.co.uk, or visit us at 95 Mortimer Street, London W1W 7GB. |
