Filing Self Assessment can feel daunting, particularly if you’re uncertain about deadlines and potential penalties. But don’t worry – this guide will walk you through the essential Self Assessment tax dates for 2025, ensuring that you can plan ahead and file your returns on time. By the end of the article, we hope you will feel fully in control of your tax deadlines this year.
What Is Self Assessment?
Income Tax Self Assessment, or simply Self Assessment, is a system of tax collection used by HMRC. It is used widely to collect Income Tax from individuals such as sole traders or self-employed landlords. This is because, unlike regular employees, self-employed people do not have their tax automatically deducted via PAYE. Instead, the self-employed must file their own tax return (Self Assessment) to report earnings and calculate/pay their tax liability.
Who Needs to Submit a Self Assessment Tax Return?
Sole traders
Sole traders (self-employed individuals) currently only need to file Self Assessment if earnings exceed £1,000 within the tax year. Even if you submit a Self Assessment, it does not necessarily mean that you will need to pay Income Tax on your earnings – especially if you earn no more than £12,570 (the current “personal allowance”).
Landlords
For landlords, it is slightly more complex. You must report rental income if you earn more than:
- £2,500 (after allowable expenses)
- £10,000 (before allowable expenses)
The first £1,000 of your property rental income is tax-free (your “property allowance”). If you earn between £1,000 and £2,500 from property rental in one tax year, you must contact HMRC.
Others
In addition to sole traders and landlords, there are other individuals who might require Self Assessment due to untaxed income. These can include:
- Partners in business partnerships
- People receiving income from investments
- Individuals receiving foreign income
- High earners (with PAYE salary exceeding £150,000)
There are several other supplementary pages available for Self Assessment returns, corresponding to specific income types and scenarios (such as Lloyd’s of London underwriting income, trust beneficiaries and settlors, capital gains, or non-UK residency/domicile).
Key Self Assessment Deadlines for 2025
Let’s review the key Self Assessment tax dates for this year:
31 January 2025: Self Assessment tax return (online)
This is the final date to submit your completed Self Assessment tax return for 2023/2024 online. HMRC must receive it before midnight. However, in the event of an error, it is possible to submit an amended return later (within 12 months).
31 January 2025: Pay tax bill
In addition to submitting your Self Assessment tax return, you must also pay any tax due (your Self Assessment tax bill). The deadline for both of these is the same, so it is important to plan ahead!
31 January 2025: Make first payment on account
By this deadline, you might also need to pay your first payment on account. This is typically 50% of the most recent tax bill, paid towards next year’s tax bill. You may not be requested to pay this if:
- Your most recent tax bill was below £1,000
- More than 80% of your Income Tax is deducted at source via PAYE
5 April 2025: End of tax year
The tax year officially ends at midnight, with the new tax year beginning 6 April. For most people running small businesses, using cash basis accounting, this means that any income or expenses after this point will fall under the next tax year.
Although cash basis accounting is now the default method, there is also traditional accounting. Traditional accounting reports the date of invoicing or billing (rather than the date when you received money or paid a bill).
For example, if you send an invoice on 1 April 2025 and receive payment on 7 April 2025, this will be:
- Reported under the 2024/2025 tax year in traditional accounting
- Reported under the 2025/2026 tax year in cash basis accounting
Since cash basis accounting is the default method for Self Assessment returns, you must choose to opt out if you wish to use traditional accounting instead.
31 July 2025: Make second payment on account
If you make payments on account, the second instalment will be due now. This should be equal to 50% of your previous tax bill, and equal to the amount you paid in January.
5 October 2025: Register for Self Assessment
If you have never filed Self Assessment before, or if you did not file Self Assessment last year, you must register. By registering, you notify HMRC in advance that you will be submitting a tax return this year.
31 October 2025: Self Assessment tax return (paper)
If you are submitting a paper-based Self Assessment return – instead of the online Self Assessment return – then it will be due today. Note that paper returns are rare, and the online deadline is considerably later (in the following January).
This is also the deadline for paper returns if you wish to pay your Self Assessment tax bill via PAYE.
30 December 2025: Deadline for tax collection through PAYE (online)
If you wish for HMRC to collect your Self Assessment tax bill via PAYE, you must submit your Self Assessment online by this date. This is only possible if your tax bill is below £3,000 and you already pay tax through PAYE (e.g., as an employee or for a company pension).
Consequences of Missing Self Assessment Deadlines
It is a legal requirement to report income and pay tax on time. As a result, missing a Self Assessment deadline can lead to penalties imposed by HMRC. At present, missing a submission deadline or payment results in an immediate fine of at least £100.
Failure to comply fully within three months of the deadline will result in further fines. If you continue to fail to comply, you should expect to pay increased fines with added interest.
When MTD for ITSA arrives, there will be a new penalty points system in place. Points will be added to your account each time you miss a deadline. After reaching certain numbers of points, fines will be imposed.
It is essential that you keep on top of deadlines. However, if you believe you are undergoing exceptional circumstances, you may be able to request an extension to a Self Assessment deadline and avoid a penalty. We have written an article on this topic with more details. Note that such extensions, although not impossible, are rarely granted.
Read on below for tips to avoid such consequences!
Tips to Stay on Top of Self Assessment Deadlines
Set up regular reminders
If you want to avoid a last-minute rush, plan ahead and set reminders on your digital calendar (or physical calendar!). Many calendar apps/programs allow you to set recurring reminders – e.g., before 31 January each year, so you can simply set them once and put your mind at rest.
Keep digital records throughout the year
Keeping tidy and regularly updated records is key to a smooth Self Assessment experience. Waiting until the last minute to put together your finances is never a good idea, and can lead to unnecessary stress and inaccuracy.
By using digital software for recordkeeping – which will soon be mandatory for many taxpayers anyway – you can also reduce human error and quickly create backups to store in safe places. Make sure to document all business income, expenses and any other relevant finances, and maintain long-term records.
Seek professional help if needed
If you think your financial situation is too complex to manage alone, or you are unsure, it could be wise to contact a professional (e.g., an accountant or tax adviser). Make sure to contact them well in advance of any deadlines to prevent stress and/or extortionate fees for an urgent consultation.
Plan ahead for tax payments
If you are expecting to pay a tax bill, you might want to plan ahead by setting aside a portion of income regularly to cover it. By doing this, you could avoid any last-minute strain on your budget or personal finances when Self Assessment tax dates arrive.
How Software Can Help You Stay on Top of Your Tax Returns
As digital technology advances, software continues to simplify processes and save us time. When it comes to Self Assessment, AbraTax provides a stellar service in this regard. Whether you’re a sole trader, landlord, or have other income to declare, we currently provide free and personally tailored Self Assessment returns.
With step-by-step guidance and an automated tax calculation, you can submit your Self Assessment with ease and on time with our HMRC-recognised software. Not only do we incorporate form validation (error-checking), but you can submit directly to HMRC, receiving instant confirmation.
Conclusion
Staying on top of Self Assessment tax deadlines is crucial to avoiding penalties and unnecessary stress. By planning ahead, setting reminders, and using bespoke software such as AbraTax, you can expect a much smoother tax experience. AbraTax Self Assessment helps you meet deadlines and file accurately in a user-friendly environment – currently for free. Why not get ahead in 2025 by registering for AbraTax Self Assessment today?