Eight reasons you may need to register for self-assessment before 5 October
From claiming pension tax relief to having a side hustle, there are lots of reasons why you may need to register for self-assessment, and the 5 October deadline is approaching fast.
The deadline to register for a self-assessment tax return is now less than a month away.
Although the deadline to submit your tax return is in January, those who have not completed self-assessment before or did not need to submit a tax return in the 2024/25 tax year will need to make sure to register before the 5 October deadline or risk facing a penalty.
The most common reason you may sign up for self-assessment is because you are self-employed.
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But there are many other reasons you may need to submit a tax return to HMRC – even if you do not expect to pay any tax this year.
Myrtle Lloyd, chief customer officer at HMRC, said: “Anyone new to Self Assessment may not realise they need to register before they can submit their tax return” but noted that “registering is quicker and easier than ever” and that registering soon will leave plenty of time to complete a return before the 31 January deadline.
If you think you may need to file a tax return this year, you can check through HMRC’s online tool. If you’re unsure, here are 8 reasons you may need to register for self-assessment.
1. You work for yourself or you’re in a business partnership
If you are self-employed or in a business partnership, you will not pay tax through Pay As You Earn (PAYE).
That means you need to tell HMRC how much you earned in the tax year and then pay the tax due through self-assessment. You will likely have to make two payments each year, one by 31 January and the other by 31 July.
2. You’re a buy-to-let landlord
If you rent out a property and earn any money through it, you will need to declare this income to HMRC. And if the 2025/26 tax year is your first as a buy-to-let landlord, you will need to register for self-assessment in order to pay it.
3. You’re a higher-rate taxpayer who pays into a pension
If you are a higher-rate taxpayer (earning between £50,271 and £125,140 a year) and pay into a personal pension like a SIPP, or your employer runs a scheme on a “relief at source” basis, you may need to register for self-assessment to claim your full tax relief.
Higher-rate taxpayers can claim an extra 20% while additional-rate payers can get a further 25%.
If your employer makes contributions before tax, you’ll receive the full pension tax relief automatically and you don’t need to tell HMRC. The same is true if you have a salary sacrifice arrangement.
But if you contribute to your pension through “relief at source” or pay into a SIPP, you may need to file a tax return.
If you’re not sure how your workplace pension works, check with your HR team or your pension provider.
If you have extra relief to claim, you can either complete a tax return, or if you’re employed you can write to HMRC and receive a one-off payment.
4. You’re a higher-rate taxpayer who gives to charity
You automatically get 20% gift aid when you donate to charity, but you can claim back the rest of the tax relief through a self-assessment claim.
However, if this is your only reason for completing a tax return, there are alternatives. You can fill in a separate form to make the claim, or contact HMRC and ask them to amend your tax code instead.
5. You make £10,000 from dividends
If you make £10,000 or more in dividends, you will need to report this to HMRC by filling in a self-assessment tax return.
If you get less than £10,000 in dividends, you will still need to pay any tax due, but this is not done through self-assessment.
6. You invest in an EIS or VCT
Some investments like the Enterprise Investment Scheme (EIS) and Venture Capital Trusts (VCTs) come with tax benefits. To claim these, you will need to sign up for self-assessment.
However, if this is your only reason for filing a tax return, you can arrange for the tax to be repaid through an amendment to your tax code.
7. You have a side hustle and make more than £1,000 a year
If you have started a ‘side hustle’ like selling items on eBay or Vinted, or being paid to babysit or walk dogs, you may need to register for self-assessment if you earn more than £1,000.
Everyone has a £1,000 trading allowance, but any money earned above this will have to be declared and taxed by HMRC. That means you need to complete self-assessment.
8. You rent out a spare room, and make more than the rent-a-room limit
The rent-a-room limit allows you to earn up to £7,500 a year tax-free when you rent out a furnished room in your home, including through services like Airbnb.
However, if you earn more than £7,500, you will need to declare this to HMRC through self-assessment.
