For most employees, tax is simple - it’s taken at source through PAYE and there’s nothing extra to do. But if you’ve started earning additional income outside of your main job, you might need to register for Self Assessment. The deadline to register for the 2024/25 tax year is 5 October 2025. If you've missed the 5 October deadline, don't panic! Just follow the steps, and get your tax return filed and paid by 31 January 2026 to avoid more HMRC nasties.
How the tax year works
The UK tax year runs from 6 April to 5 April the following year.
So:
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If you earned extra income between 6 April 2024 and 5 April 2025, you need to register by 5 October 2025.
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Your tax return (and any payment due) will then be filed by 31 January 2026.
The £1,000 trading and property allowances
HMRC gives two handy allowances:
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Trading allowance: If your total income from self-employment or casual work is £1,000 or less in the year, you don’t need to register or pay tax on it.
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Property allowance: Similarly, if your total income from property rental is £1,000 or less in the year, you don’t need to register or declare it.
If you earn more than £1,000 from either, you’ll need to register for Self Assessment and declare the income - even if you’ve already paid some tax elsewhere (like through PAYE).
Who else needs to register?
You’ll usually need to register if you:
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Are self-employed and earned more than £1,000 (before expenses).
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Are a partner in a business partnership.
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Earn income from property rental above £1,000.
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Receive dividends, interest, or investment income not taxed at source.
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Made profits from selling assets (e.g. shares or property).
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Need to claim certain reliefs, such as pension tax relief or Gift Aid.
Why act now?
HMRC is getting sharper at matching data - from rental platforms to bank interest. If you’ve been earning but not declaring, it’s better to come forward than wait to be asked. Voluntary disclosure often means reduced penalties, especially for landlords using HMRC’s Let Property Campaign.
How we help
At Donaldson Ross & Co, we:
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Advise whether you need to register (and help you do it).
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Prepare and file your return accurately and on time.
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Support with disclosures if you’ve missed something in the past.
Unsure if you need to register? Don’t guess. Talk to us, and we’ll make sure you’re covered.