Have you submitted your self assessment tax return?

According to HMRC, millions still need to file their Self Assessment tax return before the deadline on 31 January 2026. But what exactly is a Self Assessment tax return and how do you go about filing one?

If you're self-employed, you will need to submit a Self Assessment tax return every year in order to pay income tax and National Insurance on your profits for the previous year.

This year's deadline for submitting your Self Assessment return online and paying your tax for the 2024 to 2025 tax year is 31 January 2026. If you miss the deadline, you could incur penalties, which is why it's important to get on top of things as soon as possible. But it doesn't need to be so overwhelming. 

Mike Parkes, technical director at GoSimpleTax said, “The idea that self-employed life can be ‘feast or famine’ is one that often sees many self-employed workers concentrating solely on getting their invoices paid, and not always thinking about what comes next.

“This can sometimes mean that there isn’t income put aside for tax, or for other financial security like investments, pensions, and savings. This can then have a knock-on effect so that when the January deadline for Self Assessment comes round, it can mean scraping together money to pay the amount owed rather than being prepared and having it ready and set aside.”

Parkes continued, “Having control of finances, including paying tax and budgeting, are two of the sides of self-employed life that can often be time consuming and draining but they don’t have to be. 

"Getting ready for the 31 January 2026 deadline can mean taking the headache out of paying tax and help it seem less of a drain on your finances too.”

What Exactly is Self Assessment?                                                     

Self Assessment is how the self-employed and sole traders pay tax on their income.

People are usually taxed automatically through their pay from their employer, but if you’re self-employed as a contractor or freelancer or if you haven’t been automatically taxed, for instance you rent out a property, you may need to declare your income by completing a tax return and then pay any tax owed.

The current Self Assessment reporting period is for 6 April 2024 to 5 April 2025.

How to check if you need to file a tax return

If you’re new to Self Assessment and not sure where to start, you can use the ‘check if you need to send a tax return’ tool on GOV.UK. You simply answer a few straightforward questions and the tool helps you decide if you need to complete a tax return.

How to get started with a Self Assessment

If you are new to Self Assessment for the 2024 to 2025 tax year,  you’ll first need to register for Self Assessment. You can watch HMRC's helpful YouTube videos which take you through the online registration process every step of the way.

Once you have registered, HMRC will send you your Unique Taxpayer Reference (UTR) – a 10 digit reference number that is used to identify your Self Assessment tax record. Your UTR is also stored in the HMRC app or your online account. 

You can complete your tax return online via GOV.UK. When you’re ready to start your tax return you’ll need your UTR and National Insurance number, as well as details of your income, earnings, savings interest and other financial records. 

Information to include on your tax return

You’ll need to include all your taxable income on your tax return so you can pay any tax owed. So that’s any income you have already paid tax on (for example, if you’re employed and paid Income Tax and National Insurance through PAYE) as well as any expenses so we can accurately calculate if any tax is due.

You’ll also need to include information on any contributions you’ve made to charity or pensions that may be eligible for tax relief.

Make sure you keep records such as bank statements, invoices, contracts and receipts for your income and outgoings.

Can someone else fill in your self assessment in for you? 

Yes, you can authorise an agent to manage your tax affairs (such as an accountant or tax adviser) or ask a friend or relative or give someone power of attorney to act on your behalf. But it’s worth remembering it remains your responsibility to ensure the return is accurate and submitted on time. It's important to note that you should never share your HMRC login details with anyone, including your tax agent.

How to pay Self Assessment tax

The deadline to pay any Self Assessment tax owed is 31 January 2026 and the quickest and easiest way to pay is through the HMRC app. 

If you think you may struggle to pay your tax bill, simply get in touch with HMRC to let us know. There are a range of payment options, that could be available to you including a Budget Payment Plan where any payments you make will be used to pay your next tax bill.

You may be able to set up a payment plan yourself. The plan, known as a ‘Time to Pay’, means eligible customers can arrange to pay their tax bill in regular instalments over an agreed period.

What You Need to Know About Making Tax Digital (MTD)

Making Tax Digital (MTD) is coming into force on 6 April 2026. Taxpayers who report a gross income of more than £50,000 from self-employment or property in their 2024/25 self-assessment will need to comply by keeping digital income records using MTD-compliant software.

Failing to meet the requirements may result in fines of up to £200 under a new points-based system. Experts have warned against attempting to underreport income to avoid meeting the MTD threshold. 

Parkes, also of Coconut, record-keeping software approved for Making Tax Digital, said, “Making Tax Digital has been on the horizon for years, and now the countdown is real. Taxpayers need to start preparing to move onto digital accounting software to stay compliant.

"Any change in regulations can feel overwhelming, but trying to tweak your numbers to avoid falling into MTD’s threshold is a bad idea.

"The system is designed to make reporting more accurate, so discrepancies will be easily noticed and could land you in hot water with fines, penalties or even criminal convictions.”

“Don’t try to avoid the inevitable. Wider thresholds are set to be rolled out so anyone earning over £30,000 from self-employment or property in the current tax year will need to comply with Making Tax Digital from 2027.

"The threshold is set at £20,000 for the following year. Starting to use compliant software will save stress and time in the long run.”

Looking ahead to next year

If you have left it to the last minute, don’t beat yourself up over it but try and learn from it for next year.

Good financial management is about getting into the habit of staying on top of the pennies and pounds. It’s easy to neglect the paperwork when you’re busy working, but you’ll thank yourself for doing it when the time comes to do next year’s Self Assessment.

Start putting away money for taxes as soon as possible, so you're able to cover the payment next year. “Budgeting for the tax bill is another challenge that grows the longer it’s left," says Parkes.

"Our research found that one in five (20%) self-employed people had no idea how much they owe, and a further 15% knew the amount but had yet to find the funds.

"Many self-employed people are dealing with irregular income and tight margins, which makes cash flow tricky. The earlier the tax return is completed, the sooner workers know exactly what they need to pay, giving them more time to plan and avoid late payment charges.”