Britons could be slapped with an automatic fine from HM Revenue and Customs (HMRC) if they fail to meet a fast approaching deadline.
Taxpayers have only a couple of days remaining to register for Self Assessment as the deadline for filers falls on October 5, 2025.
Andrea L Richards, the chief executive of Accounts Navigator, cautions that households could face penalties reaching £1,600 if they continue to delay.
The registration requirement applies to various groups including self-employed individuals earning above £1,000, business partners, those liable for capital gains tax (CGT), and recipients of untaxed income such as rental earnings or foreign income.
Britons are being reminded of their liabilities
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"Anyone needing to submit a tax return for the first time must notify HMRC by October 5, 2025," Ms Richards states.
Those who register late receive an extended filing period of three months from when HMRC issues their return notice.
However, Richards emphasises that postponing registration heightens the likelihood of incurring penalties if submissions arrive late.
The second crucial date looms on October 31, when paper tax returns for the 2024/25 year must reach HMRC.
Are you on to of your taxes?
| GETTY"People might think that if they miss the paper deadline, filing online by January 31 2026 will automatically avoid penalties, but HMRC calculates late filing penalties from the date the first return is received," Ms Richards explained.
Penalties intensify significantly for those who continue to delay. Returns submitted over three months late incur daily charges of £10, potentially accumulating to £900.
After twelve months, another £300 or five per cent penalty is imposed.
"In total, penalties for serious delays can reach £1,600, in addition to any tax owed," Ms Richards warned.
Complete failure to file carries severe consequences. HMRC possesses the authority to estimate tax liabilities and demand immediate payment with interest.
In extreme circumstances, the tax authority may initiate court proceedings against non-compliant taxpayers.
Significant changes await taxpayers from April 2026 when Making Tax Digital for Income Tax replaces the current system.
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Self-employed individuals need to file their tax returns | GETTYGeorge Holmes, managing director of Aurora Capital, explains that the single annual deadline will be replaced by five submissions throughout the year.
"Under the old Self Assessment rules, a late filing meant an immediate £100 fine," Holmes notes. "From April 2026, the system will look very different."
The new framework introduces a points-based penalty system where each missed deadline earns a penalty point, with a £200 fine only applying after accumulating four points.
Payment penalties will also tighten, beginning after just 15 days rather than the current 30-day grace period.