Self Assessment is HMRC’s way of collecting Income Tax from individuals who don’t have it automatically deducted through PAYE (Pay As You Earn). If you earn income that HMRC doesn’t automatically know about—such as freelance earnings, rental income, or overseas earnings—you’re responsible for reporting it yourself.
In this article
Who Needs to File Tax Return?
Not everyone needs to worry about filing, but here are the most common scenarios where it’s required:
- Self-employed individuals or sole traders who earned more than £1,000 during the tax year.
- Partners in business partnerships.
- Landlords receiving rental income.
- Anyone with untaxed income, including from investments, dividends, or crypto.
- People who receive foreign income.
- Those who sold assets (like property or shares) and need to report Capital Gains.
- Company directors (unless all income is taxed through PAYE).
- If your income exceeds £100,000 in a tax year.
- You or your partner claimed Child Benefit and one of you earned over £50,000.
Note: From the 2024/25 tax year, HMRC no longer requires Self Assessment filings from taxpayers earning over £100,000 if all income is taxed under PAYE. This is a welcome simplification for high earners with no extra sources of income.
If you’re unsure, HMRC has an online tool you can use to check if you need to file.
Key Deadlines
Dates matter when it comes to taxes. Here are the big ones:
- 5 October 2025 – Deadline to register for Self Assessment if you’re filing for the first time (e.g. new self-employment or rental income during the 2024/25 tax year).
- 31 October 2025 – Deadline for filing a paper tax return.
- 31 January 2026 – Final deadline for filing online and paying any tax due for the 2024/25 tax year.
How to Tax Return
Filing your return online is the most convenient option. If it’s your first time, here’s a step-by-step:
- Register with HMRC – You’ll receive a Unique Taxpayer Reference (UTR), which you’ll need for your tax return.
- Set up a Government Gateway account – This gives you access to your personal tax account.
- Complete your return online – Log in and follow the prompts. Have your income figures, allowable expenses, and records ready.
- Submit and pay – Once everything is completed, you’ll be given a summary of your tax bill, and you can make the payment by 31 January.
It’s that simple. Though, if your situation is a bit more complex—say, you have foreign income or multiple sources of earnings—you might want to consider working with a tax adviser.
What Happens If You Don’t File?
Late filing and payment come with penalties. Here’s what you’re looking at:
- £100 fixed penalty if your return is up to 3 months late.
- Additional daily penalties of £10 per day after 3 months, up to a maximum of £900.
- If it drags on past 6 months, you could face further fines or interest charges on the tax due.
So even if you don’t owe much, it pays to file on time. Literally.
Conclusion
Filing a Self Assessment doesn’t have to be a nightmare. If you’re earning outside the usual PAYE system, it’s your responsibility to file—and file on time. Make sure you understand whether you’re required to complete one, get your documents in order early, and don’t wait until the last minute.
Whether you’re a landlord, side hustler, freelancer or earning income from abroad, knowing how to file self assessment tax return properly helps you stay on the right side of HMRC. And remember: if you’re unsure, it’s better to check than to guess.
If you’re feeling overwhelmed or your tax affairs are complex, a professional can help ensure everything is in order when it’s time to file self assessment tax return.
