Don’t miss the January tax return deadline

The tax return deadline for the 2024/25 UK tax year is fast approaching and must be met by 31 January 2026 for online submissions, so now really is the time to focus on getting Self Assessments filed and any tax owed to HM Revenue and Customs (HMRC) paid.  

Those that fail to file their tax return in time face an immediate £100 late filing penalty with daily penalties kicking in after three months and potentially further charges the longer it goes unpaid.

It is worth taking time over the preparation rather than panicking in the face of the upcoming deadline because mistakes or omissions can lead to overpaying your tax or having to go through corrections and potential appeals later on. If someone overpays once their return is processed, HMRC may pay a refund, but the interest they pay on their own late repayments is generally much lower than the interest they charge on your late payments.  

From early January 2026 the late payment interest rate charged on overdue tax was set at 7.75%, which is 4% above the Bank of England base rate, while the repayment interest rate paid by HMRC on refunds is 2.75%, substantially less than the charge on unpaid tax.  

The bottom line is that taxpayers should get their tax return ready well in advance of the end of January if possible. Check carefully that you are not paying more tax than necessary and settle any tax due on time.

What is Self-Assessment?

Self-Assessment is the process you go through each year where you complete a tax return and declare your income, capital gains and any other income during that tax year to HMRC, outside of income tax that is normally deducted from your wage or pension.  

Although most commonly done by those who are self-employed, anyone who has other income outside what is normally deducted from your wages and pension, need to complete a self-assessment form – which can be paper based or digital.  

Irrespective of employment status, if you have received any untaxed income before the deadline of that tax year, you may need to complete a tax return. Even if that income comes from eBay, Etsy or similar ‘side hustle’ enterprises.

When you need to submit a tax return

This tax year (2025/26) ends on 5 April 2026 and all tax returns for this year will need to be completed by 31st January 2027.

Most importantly, you must tell HMRC by 5 October if you need to complete a tax return and have not sent one before. Then there are different deadlines for different types of tax returns.

If you’re doing a paper tax return, you needed to submit it by midnight 31 October 2026. HMRC must receive a paper tax return by 31 January 2027 if you’re a trustee of a registered pension scheme or a non-resident company.  

If you’re doing an online tax return, you must submit it by midnight 31 January 2027, and if you want HMRC to automatically collect the tax you owe from your wages and pension, then you needed to submit your online tax return by 30 December 2026.

In all cases you need to pay the tax you owe by midnight 31 January 2027.  

If you’re interested in finding out more about how we can help you build a tax efficient portfolio, making best use of allowances available to you whilst ensuring your money is working hard, Why not give us a call on 0333 323 9065 or book a free non-committal initial consultation with a member of our team.

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This article is intended for general information only, it does not constitute individual advice and should not be used to inform financial decisions.  

The Financial Conduct Authority (FCA) does not regulate tax or trust advice.