Don’t Miss the 31 January Tax Deadline – Your Complete Guide and Top Tips.

Published 14th January 2026

It’s that time of year again – the Self-Assessment tax deadline is fast approaching on 31 January. Whether you’re submitting a return yourself, helping a client, or preparing for your business year-end, understanding what’s due and how to avoid penalties can save you stress and money.

Here’s what you need to know, and how to get ready in good time.

What is the 31 January Deadline?

Each year, individuals and business owners who complete a Self-Assessment tax return must file their return and pay any tax owed by 31 January. This deadline applies to:

Online tax return submissions

Payment of your tax bill for the previous tax year

First payment on account for the next tax year (if applicable)

For the 2024 to 2025 tax year, this means filing and paying by 11.59pm on 31 January 2026.

If you miss this deadline, HMRC automatically charges a £100 late filing penalty, even if you do not owe any tax.

Why Early Filing Pays

Filing your return early has several clear advantages:

1. Know What You Owe Sooner

Filing early means you can see your tax bill ahead of time and prepare for it financially.

2. More Time to Budget or Pay in Instalments

Once you know your liability, you can:

• Budget for the amount you owe

• Set up repayment plans with HMRC

• Avoid last-minute cash flow stress

3. Lower Risk of Penalties

Late returns can quickly lead to penalties that grow over time. After the initial £100 fine, HMRC may apply daily penalties and interest if your return and payment are late.

Do You Have to File a Return Even If You Don’t Owe Tax?

Yes – if HMRC has asked you to complete a Self-Assessment tax return, you must file it by the deadline even if:

You expect a refund

You paid all your tax via PAYE

You have no tax to pay

Failing to file on time can result in a penalty, regardless of whether you owe tax.

Key Dates to Remember

Here’s a quick reference for the most important deadlines:

5 October 2025 – Deadline to register for Self-Assessment if you’re new to the system.

31 October 2025 – Last date to file a paper tax return.

31 January 2026 – Online return deadline and payment due date for the 2024–25 tax year.

31 July 2026 – Second payment on account due (if applicable).

For most filers, the online route is now standard practice and offers more time than the paper option.

How to File and Pay

Filing Your Return

You can submit your Self-Assessment return online via your HMRC tax account. This is secure, fast and lets you check your figures before submitting.

Keep records of all your income and expenses before you start. Collect:

Payslips and P60/P45s

Details of self-employment or rental income

Dividend and interest statements

Business receipts and allowable expenses

Paying What You Owe

You must pay any tax due by 31 January.

This includes:

The balancing payment for the previous tax year

Your first “payment on account” for the next tax year (if applicable)

If you struggle to pay in a lump sum, HMRC allows payment plans so you can spread the cost weekly or monthly.

Top Tips to Stay on Track

Start Early

Don’t leave your return until the last minute. HMRC’s own reminders highlight that early filing helps you avoid the rush and gives you breathing space to check figures and get help if needed.

Double-Check Your Numbers

Errors can lead to HMRC queries or even penalties. Make sure your income, allowances and deductions are accurate.

Stay Organised All Year

Good bookkeeping makes completion easier. Keep digital copies of receipts and record all income streams as they arise.

Watch Out for Scams

HMRC will never ask for personal or bank details by text or email. If you get a suspicious message mentioning your tax return or refund, check it in your official HMRC account and report anything unusual.

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