If you complete a Self Assessment tax return, keeping track of the important deadlines is essential. Missing a deadline can result in unnecessary penalties and interest from HMRC, even if you don’t owe any tax.
Whether you’re self-employed, a company director, a landlord or have additional income outside of PAYE, understanding the Self Assessment deadlines for 2026 will help you stay compliant and avoid last-minute stress.
At King & Taylor, we’ve been supporting individuals and businesses across Gravesend, Kent and the surrounding areas with professional accountancy and tax services for over 150 years. This guide explains the key dates you need to know and how our experienced team can help.
What is Self Assessment?
Self Assessment is HMRC’s system for collecting Income Tax from people whose tax cannot be automatically deducted through PAYE.
You may need to complete a Self Assessment tax return if you are:
- Self-employed or a sole trader – read more about becoming a sole trader on the government website.
- A company director
- A landlord earning rental income
- A business partner
- Receiving income from investments or overseas assets
- Earning untaxed income above HMRC thresholds
If you’re unsure whether you need to submit a return, our team at King & Taylor can advise you.
Self Assessment Deadlines for 2026
The following deadlines apply during the 2026 tax year.
5 October 2026
Register for Self Assessment
If you’ve never submitted a tax return before, you’ll usually need to register with HMRC by 5 October 2026 following the end of the tax year in which you first became liable.
Registering early helps ensure you receive your Unique Taxpayer Reference (UTR) in plenty of time.
31 October 2026
Paper Tax Return Deadline
If you’re submitting a paper tax return rather than completing it online, it must reach HMRC by 31 October 2026.
Most taxpayers now choose to file online, which provides additional time.
31 January 2027
Online Tax Return Deadline
The majority of taxpayers submit their return online.
Your online Self Assessment tax return must be submitted by 31 January 2027.
This is also the deadline for paying any tax owed for the previous tax year.
31 January 2027
First Payment on Account
Depending on your circumstances, you may also need to make your first Payment on Account towards your next year’s tax bill.
This often catches taxpayers by surprise, so it’s important to budget accordingly.
31 July 2027
Second Payment on Account
If Payments on Account apply to you, your second instalment will normally be due by 31 July 2027.
What Happens if You Miss a Self Assessment Deadline?
HMRC issues automatic penalties if deadlines are missed.
These can include:
- An immediate late filing penalty
- Daily penalties for continued delays
- Interest on unpaid tax
- Additional penalties for prolonged non-compliance
Even if you cannot afford to pay your tax immediately, it’s usually better to submit your return on time and speak to HMRC about payment options. Read more about the late payment penalties here.
Tips to Avoid Last-Minute Stress
Many people leave their tax return until January, creating unnecessary pressure.
We recommend:
- Keeping accurate records throughout the year
- Tracking business expenses as they occur
- Setting aside money for your tax bill
- Completing your tax return well before the deadline
- Speaking to an accountant if you’re unsure about allowable expenses
Preparing early often results in a more accurate return and gives you more time to plan for any tax due.
Why Choose King & Taylor?
At King & Taylor, we’ve been helping businesses and individuals with tax and accountancy services since 1873.
Our experienced accountants support clients across Gravesend, Kent, Dartford, Medway, Rochester, Chatham, Gillingham, Sittingbourne and the surrounding areas.
Whether you need help with a straightforward Self Assessment return or more complex tax affairs, we provide clear, practical advice tailored to your circumstances.
Our services include:
- Self Assessment tax returns
- Limited company accounts
- Corporation Tax
- Payroll
- VAT
- Bookkeeping
- Business advice
- Tax planning
Frequently Asked Questions
When is the Self Assessment deadline for 2026?
The deadline for online Self Assessment tax returns is 31 January 2027, while paper returns must be submitted by 31 October 2026.
Can an accountant complete my tax return?
Yes. An accountant can prepare and submit your tax return on your behalf, ensuring it is completed accurately and on time.
What happens if I submit my tax return late?
HMRC may charge automatic penalties and interest depending on how late your return and payment are.
Can I file my tax return early?
Absolutely. In fact, filing early is often recommended, as it gives you more time to budget for any tax due.
Need Help with Your Self Assessment?
Completing a tax return doesn’t have to be stressful.
Whether you’re self-employed, a company director or a landlord, the team at King & Taylor is here to help.
If you’re based in Gravesend, Kent or the surrounding areas, contact King & Taylor today for friendly, professional advice on your Self Assessment tax return. We’ll make sure everything is submitted accurately, on time and in line with the latest HMRC requirements, giving you complete peace of mind.
