HMRC says more than 11.48 million people filed on time last year, but around one million missed the deadline. Here is how to prepare for 31 January 2027 and avoid unnecessary penalties.
More than 11.48 million people submitted their Self Assessment tax return by the 31 January 2026 deadline, according to HM Revenue and Customs (HMRC). However, an estimated one million taxpayers missed the deadline, while 475,722 waited until the final day to file.
The figures show that many people still leave Self Assessment until the last possible moment. Preparing early can help you avoid last-minute problems, understand your tax bill and reduce the risk of penalties.
Next online filing and payment deadline
11:59pm on 31 January 2027
What the latest HMRC figures tell us
HMRC expected more than 12 million returns for the 2024 to 2025 tax year. By 31 January 2026, it had received 11,489,825 returns, with 97.25% submitted online.
Deadline day was particularly busy:
• 475,722 returns were filed on 31 January
• 32,982 were submitted between 5pm and 6pm, the busiest hour
• 27,456 were filed during the final hour before midnight
Online filing is convenient, but waiting until the final hours can still be risky. Missing records, forgotten login details, an unexpected tax calculation or a technical problem could prevent you from filing on time.
Key Self Assessment deadlines for 2025 to 2026
The return due in January 2027 covers income received during the tax year from 6 April 2025 to 5 April 2026.
| Deadline | What is due? |
|---|---|
| 31 October 2026 | Deadline for most paper tax returns. |
| 30 December 2026 | Online filing deadline if you want HMRC to consider collecting eligible tax through your PAYE tax code. |
| 31 January 2027 | Deadline for most online returns and payment of the tax due. |
If you registered for Self Assessment after 5 October 2026, HMRC should provide a separate filing deadline, normally three months from the date of its letter or email. However, any tax due must still normally be paid by 31 January 2027.
Why you should file early
Know your tax bill sooner
Filing early confirms how much tax you owe and gives you more time to plan the payment. Submitting your return early does not normally mean that you must pay early. The usual payment deadline remains 31 January 2027.
Allow time to find missing information
Your return may require details of employment income, self-employment income, rental income, bank interest, dividends, pension contributions, allowable expenses or capital gains. Starting early gives you time to collect the correct records and resolve any differences.
Reduce mistakes caused by rushing
A rushed return can lead to missing income, duplicated figures or incorrect expense claims. Preparing the return with enough time for proper checks helps improve accuracy.
Deal with payment problems promptly
If you cannot pay your bill in full, you should still submit the return on time. Eligible taxpayers may be able to arrange a Time to Pay plan with HMRC. Interest may continue to apply, so it is better to address the issue early.
What happens if you file late?
HMRC's late-filing penalties can increase over time:
• An initial £100 penalty, even if there is no tax to pay or the tax is paid on time
• After three months, daily penalties of £10, up to a maximum of £900
• After six months, a further penalty of 5% of the tax due or £300, whichever is greater
• After 12 months, another 5% of the tax due or £300, whichever is greater
Late-payment charges are separate
Separate late-payment penalties may also apply at 30 days, six months and 12 months. HMRC can also charge interest on unpaid tax.
What should you prepare?
Depending on your circumstances, you may need:
• Your Unique Taxpayer Reference and online sign-in details
• P60, P45 or P11D documents
• Self-employment income and expense records
• Rental income and property expense records
• Bank interest and dividend statements
• Pension contribution and Gift Aid details
• Information about capital gains
• Details of any payments on account already made
What if you no longer need to file?
If you have stopped being self-employed, stopped renting out property or believe you no longer need to submit a return, do not simply ignore it. You should notify HMRC as soon as possible and wait for confirmation that the filing requirement has been removed.
Prepare before the January rush
The latest HMRC figures make the lesson clear: hundreds of thousands of taxpayers still wait until deadline day, and around one million miss it altogether. Filing early gives you time to check the figures, plan the payment and resolve problems before penalties arise.
How Number One Accounting can help
Number One Accounting can help you prepare and submit your Self Assessment tax return accurately and on time.
Call: 020 3026 5008
WhatsApp: +44 7383 685130
Email: info@numberoneaccounting.com
This article provides general information only and does not constitute tax or financial advice. Individual circumstances differ, and HMRC guidance may change.