Get ready to file your self-assessment tax return

The deadline for self-assessment tax returns is 31st January. Here’s how you can prepare.

Getting your documents organised lets you file your tax return early and avoid last-minute stress. Here’s what you need to know.

Deadlines and payments

The HMRC deadline to file your online tax return and pay the amount due is 31st January after the end of the previous tax year. For example, the 2025/26 tax year ended on 5th April 2026, so your return and payment are due by 31st January 2027. You can submit your tax return at any point after the end of the tax year, as long as HMRC receives it by the deadline.

HMRC has also introduced payments on account, where you make an additional payment towards your tax bill by 31st July. If you owe more than £1,000 in tax, you’ll need to pay 50% towards next year's bill. HMRC calculates the figure based on your last return. If you make more or less than expected, they’ll adjust the figure when you file your return after the tax year ends.

What information do you need to include?

When you file your self-assessment tax return, you must include details of all your sources of income. These include payments you receive from your business, any property rentals, and interest on savings, among other things. If you have any questions about what income applies, give us a call. If you receive the Winter Fuel Allowance, you also need to include it on your tax return.

You should also keep details of your allowable business expenses, as you can deduct these from your income and reduce your tax bill. These include essential business expenses like staffing costs, employee benefits and office equipment. Some expenses have financial limits on what you can claim, while others aren’t allowable for tax purposes. We’ll always check that you follow the rules when completing your accounts and filing your tax return, but let us know if you’re unsure what’s allowed.

Make sure you keep records and documents showing your income and expenses.

Be nice to your accountant

Getting your documents in order early and sending them to your accountant well in advance of the tax return deadline avoids unnecessary stress for you and them. It gives us time to review the paperwork, finalise your accounts and file your tax return well before the deadline.

If we have any questions to help us verify the figures, we have plenty of time to ask them instead of calling you on deadline day and needing an immediate answer. We can also make sure we have all the information we need to claim any allowances you’re entitled to.

What’s more, if you have any queries once you’ve received the figure from HMRC, you have time to raise them before the payment deadline. For example, you might think the figure is wrong and want to challenge it. Filing early gives you plenty of time to discuss the figure with your accountant and make corrections before contacting HMRC.

How to pay your tax

You can pay your tax in two main ways. When you register for self-assessment, you’ll create an online Government Gateway account. You can log in to your account and use the payment link to pay your bill.

The payment method you choose depends on how close you are to the deadline.

You can send same-day or next-day payments via online or telephone banking, using a debit or credit card online, via CHAPS or by visiting your bank or building society. You can send a BACS payment, but you need to allow 3 working days for the payment to arrive. Finally, you can also pay by direct debit. If you already have a direct debit set up with HMRC, you must pay 3 days before the deadline, but allow 5 days if you haven’t set one up before.

If your account is UK-based, you can use either of the following accounts to pay HMRC:

Account name: HMRC Cumbernauld

·         Sort code - 08 32 10

• Account number – 12001039

Account name: HMRC Shipley

• Sort code - 08 32 10

• Account number - 12001020

Penalties for late filing

There are separate financial penalties if you file your tax return late, or file your return and don’t pay your tax on time.

Filing your tax return late carries an initial fixed penalty of £100. If you’re more than 3 months late, HMRC will add daily penalties of £10 per day, up to a maximum of £900. Further penalties apply if you’re over 6 months or a year late.

If you’ve filed your return but haven’t paid your tax by the deadline, you’ll be charged 5% of the tax owed at 30 days, 6 months and 12 months, plus interest.

Find out more about how the penalties work here.

Organising your financial documents and sending everything to your accountant early helps you avoid unnecessary penalties and interest, so you keep more of your money.

Whatever stage you’re at with your tax return, we’re here to help. Book a free consultation now or call us on 01664 503 700.