Register for Self Assessment by 5 October 2026: A Guide for New Sole Traders and Landlords
If you started working for yourself or began renting out a property at any point between 6 April 2025 and 5 April 2026, HMRC needs to hear from you soon. The deadline to register for Self Assessment for the 2025/26 tax year is 5 October 2026. Registering is free and reasonably quick, and doing it early makes everything that follows far less stressful.
Who needs to register for Self Assessment
You must tell HMRC by 5 October 2026 if you need to complete a tax return for 2025/26 and you have either never sent one before, or you registered in the past but did not need to send a return for 2024/25.
The most common reasons people need to register include earning more than £1,000 from self employment during the tax year, receiving rental income from a property (including a first buy to let), becoming a partner in a business partnership, or receiving untaxed income such as dividends or savings interest above the relevant thresholds.
If you are not sure whether you need to file, HMRC has a free checking tool on gov.uk, or you can simply ask our personal tax team. A quick conversation now can save a great deal of uncertainty later in the year.
Why the 5 October deadline matters
HMRC can charge a penalty if you tell them about a new source of income after 5 October. If you do miss the date, HMRC will write to you with a revised filing deadline of three months from the date of their letter, but any tax you owe is still due by 31 January 2027. Registering late therefore squeezes the time you have to prepare accurate figures and budget for your bill.
There is a practical reason to act early too. When you register, HMRC posts you a Unique Taxpayer Reference (UTR). You cannot file a return without it, and it can take a few weeks to arrive, especially in the busy autumn period. Registering now means your UTR is sitting ready long before the filing season begins.
How to register
You register through the official service on gov.uk, which walks you through a short set of questions and confirms the right route for your circumstances, whether you are a sole trader, a landlord or a new business partner. Once HMRC has processed your registration, your UTR arrives by post and your online account is ready to use.
If you would rather not deal with HMRC directly, we can handle the registration for you as your agent, make sure you are set up under the correct category, and deal with HMRC on your behalf from day one.
The deadlines that follow
Registration is only the first date in the diary. For the 2025/26 tax year, paper returns must reach HMRC by 31 October 2026. If you want any tax you owe collected through your PAYE tax code, your online return needs to be filed by 30 December 2026. The final deadline for online returns and payment is 31 January 2027. Depending on the size of your bill, you may also need to make payments on account towards the following year, with the second instalment due each 31 July.
Filing early does not mean paying early. Your payment date stays the same however soon you file, so preparing your return in good time simply gives you months of notice of exactly what you owe.
Think ahead to Making Tax Digital
Self Assessment is changing. Making Tax Digital for Income Tax went live on 6 April 2026 for sole traders and landlords with qualifying income over £50,000, and the threshold falls to £30,000 from April 2027. If you are registering for the first time now, it is the perfect moment to start with digital records from day one. Our Making Tax Digital service will set you up on the right software so quarterly reporting never becomes a scramble.
Local support wherever you are in Oxfordshire
From our offices in Witney and at Frilford near Abingdon, we support new sole traders and landlords across the county. Whether you are searching for accountants in Oxford, accountants in Bicester or accountants in Didcot, our team is nearby and happy to help you get registered, organised and confident about your first tax return.
Get ahead of the deadline
The 5 October deadline will arrive quickly, and the sooner you register, the smoother your first Self Assessment season will be. We will handle the registration, keep you on top of every date that follows and make sure you only pay the tax you need to.