1 million people miss Self Assessment deadline: What to do if you’re late

Data from HM Revenue & Customs (HMRC) has revealed that more than 1 million taxpayers missed the 31st January 2026 deadline to file their Self Assessment tax returns for the 2024/25 tax year. While approximately 11.48 million people filed their tax returns on time, those who missed the deadline now face automatic fines and interest payments. This will include those who should have submitted a tax return but did not realise they were required to file.

Who was required to submit a Self Assessment tax return?

Many taxpayers may not have realised they were required to submit a return. For the 2024/25 tax year, you generally needed to file a tax return if:

• You were self-employed: Your gross income from self-employment was more than £1,000 (the 'trading allowance').
• You had untaxed rental income: You earned more than £1,000 from letting out property or land. It is worth noting that if you let out a furnished room in your only or main home, you may not need to file a return for this income if it falls under the Rent a Room Scheme. This allows you to earn up to £7,500 per year tax-free from letting out a room. If your rental income is below this threshold, it is generally exempt from tax and does not need to be reported to HMRC via Self Assessment.
• High Income Child Benefit Charge (HICBC): You or your partner received Child Benefit and your individual 'adjusted net income' was over £60,000.
• You received high investment income: You earned £10,000 or more from savings interest or dividends outside of an ISA.
• You are a business partner: You were a partner in a business partnership.
• Capital Gains Tax (CGT): You sold assets (like shares or a second home) and your gains exceeded the £3,000 allowance, or the total proceeds from the sale were £50,000 or more, and you were registered for Self Assessment, even if you made no profit. Taxpayers with gains to report faced an added challenge due to a mid-year CGT rate change. On 30th October 2024, the main rates of CGT increased to 18% for basic rate taxpayers and 24% for higher rate taxpayers. This change may have led some to under-report or struggle with HMRC's online calculators when filing for the 2024/25 period.
• Other untaxed income: You earned more than £2,500 from other sources, such as tips or commission, that haven't been taxed.

What are the penalties for not submitting your tax return by 31st January?

If you were required to submit a Self Assessment tax return by the 31st January 2026 but failed to do so then the penalties for missing the deadline are structured to increase the longer a return remains outstanding, as shown in the table below. Even if you have no tax to pay, or have already paid your tax bill in full, the filing penalties still apply.

Delay in submitting your tax return after 31st January	Penalty Amount
1 day late	An immediate £100 fixed penalty.
3 months late	Additional daily penalties of £10 per day, up to a maximum of £900.
6 months late	A further penalty of 5% of the tax due or £300, whichever is greater.
12 months late	Another 5% or £300 charge, whichever is greater.

What to do if you missed the Self Assessment deadline?

If you have missed the 31st January deadline, you should take the following steps as soon as possible to minimise further costs:

• File your return immediately: After the initial £100 fixed penalty, daily penalties do not typically start until the return is three months late, but interest on unpaid tax starts from day one.
• Pay what you can: If you cannot pay the full amount, pay as much as possible to reduce interest charges. One of the quickest ways to pay is via the HMRC app.
• Set up a payment plan: If you are struggling to pay, you may be able to set up a 'Time to Pay' arrangement online if you meet certain criteria.
• Check if you actually need to file: Some people may be eligible to be removed from Self Assessment, for example, if their high income was previously the only reason they filed, and they now pay through PAYE. If you believe you no longer need to complete a return, you must notify HMRC to avoid further fines.

Appealing a penalty

If it is possible to appeal a HMRC penalty if you think it is unfair. HMRC will consider appeals if you have a "reasonable excuse" for missing the deadline. However, HMRC will generally not consider an appeal until the outstanding tax return has been filed.

Valid grounds for an appeal

Valid excuses for an appeal typically involve serious or unexpected events, such as:

• A recent bereavement of a close relative.
• Serious illness or a long-term hospital stay.
• Unexpected technical issues with HMRC's website.
• Fire, flood, or natural disaster.

Invalid grounds for an appeal

HMRC generally rejects appeals based on personal oversight or reliance on others. Common examples of excuses that are not considered valid include:

• Reliance on a third party: Claiming your accountant failed to submit the return is rarely accepted, as the ultimate responsibility lies with the taxpayer.
• Lack of funds: You cannot appeal a late filing penalty simply because you could not afford to pay the tax bill (filing and paying are separate obligations).
• Technical confusion: Finding the HMRC online system "too difficult" to use.
• No reminder: Claiming you did not receive a reminder letter or email from HMRC.
• Simple oversight: Forgetting the deadline or being "too busy."

You must make your appeal within 30 days of the date on your penalty notice. HMRC recommend that you pay the penalty before you appeal otherwise, if your appeal is rejected, you’ll also have to pay interest on the penalty from the date it was due. If your appeal is upheld, HMRC will repay the amount you have paid plus interest from the date you paid it. You can find out more information on how to appeal a Self Assessment penalty for late filing or late payment on the government website.