The Money Saving Expert has warned that as many as 5.6 million people could be at risk of the fine.
Martin Lewis has issued a HMRC fine warning (Image: ITV)
The Money-Saving Expert has highlighted a crucial HMRC deadline in 2026 that could result in a £100 fine. Martin Lewis explained that a £10,000 savings threshold would necessitate completing the forms. He emphasised that anyone who receives a self-assessment tax form ‘has to do it even if you think you don’t have to’.
He pointed out that the deadline is 31 January and suggested making a “rough guess” of what you owe and paying that amount beforehand if you’re unsure. This prevents the 7.75% interest from accumulating, even if you need to adjust the actual form slightly later on. In a recent video on X, Mr Lewis warned: “Do you need to do a tax return? If you do, it’s urgent. The self-assessment tax deadline is the end of this month, the 31st of January, and 5.6 million people who do need to file one haven’t done it yet.
Not doing tax returns on time can result in a fine from HMRC (Image: Getty)
He added: “If that’s you, get your skates on because if you miss a deadline, there’s a 100 quid fine, but more painfully, there’s also 7.75% interest on unpaid tax.
Who needs to heed this advice
Mr Lewis clarified: “Well, the first thing to say is anyone HMRC has told to do so. If you’ve been sent a self-assessment tax form to do it, you have to do it, even if you don’t think you have to, you have to do it. Now, that’s more likely with people who are higher 40% or additional top 45% rate taxpayers or people with complex tax affairs.
“The other main categories of who should do it if you haven’t been sent a self-assessment form are those who are self-employed and who’ve earned over £1,000 in the tax year. So remember, this is the tax year from the 6th of April 2024 until the 5th of April 2025.
“Anyone who gets child benefit and earned over £60,000 in the tax year and hasn’t opted to change your tax code so that you pay it through that way. Anyone who’s earned over £10,000 from savings interest or investment dividends in the tax year.”
With less than a month until the 31 January deadline, 54,053 individuals rang in the new year by submitting their tax return for 2024-25 on New Year’s Eve and New Year’s Day. The most popular time over the two days was between 11.00am and 11.59am on 31 December, with 3,927 people filing their return.
So far, more than 6.36 million taxpayers have submitted their tax return, but nearly 5.65 million still need to complete their self-assessment form before the deadline. Those who miss the deadline could face an initial late filing penalty of £100, followed by potential additional penalties. This £100 fixed penalty applies even if there is no tax due or if the tax due is paid on time.
HMRC has stated that individuals can begin their tax return, save it, and revisit it as many times as they need before submitting it. Once submitted, the bill does not need to be paid immediately, but it must be paid before the 31 January deadline. Individuals can set up notifications in the HMRC app to ensure they know when payments are due and avoid missing a deadline.
Those unable to meet the deadline are urged to inform HMRC before 31 January. HMRC has assured that it will treat those with reasonable excuses fairly.
1. Where to File
The official Government portal is the only place you should submit your return online. Sign in or Register to HMRC Online Services. Direct Link to File: File your Self Assessment tax return online
2. Essential Identification
Before you start the form, make sure you have these two numbers: UTR (Unique Taxpayer Reference) – a 10-digit number sent to you by HMRC, National Insurance number – found on your payslip/P60/personal tax account.
3. Document Checklist
Depending on your circumstances, you will need the following records for the tax year (April 6, 2024, to April 5, 2025):
If you were employed during the year: P60 – the income you’ve already paid tax on, P45 – if you left a job during the tax year, P11D – if you received benefits like a company car/private health insurance.
If you are self-employed or a landlord: income records – all invoices/rental receipts/a summary of your total turnover, expense records – receipts/bank statements for business costs, bank statements.
Other Income & Deductions:
Bank Interest: Statements showing any interest earned on your savings.
Dividends: Vouchers or summaries for any stocks or investments held outside an ISA.
Pension Contributions: Records of personal contributions that might qualify for tax relief.
Charitable Giving: Records of any Gift Aid donations.
Student Loan: Statements showing repayments if you are paying them back through Self Assessment.
