Millions of workers across the UK could be at risk of receiving a penalty of £900 or more
Millions of workers across the UK could be at risk of missing a critical deadline and facing penalties from HM Revenue and Customs (HMRC). The vast majority of people who are required to complete a Self Assessment must settle the tax they owe by 11.59pm on January 31, 2026.
Those obliged to submit an online tax return must also meet this deadline or risk a penalty for late submission. Many people new to the Self Assessment system will need their Unique Taxpayer Reference to properly file for the 2024/25 tax year.
Keep in mind that this deadline is only in place for people who are filing an online tax return. If you submit a paper tax return, then you were required to submit it by 11.59pm on October 31, 2025 – if you didn’t do so, you will already be subjected to penalty for a late filing.
Fines for missing the tax deadline
HMRC has the power to impose a financial penalty for any late tax returns. Beginning with a fixed £100 charge, this can rapidly escalate if overlooked.
If you don’t file your tax return within three months of the deadline, you’ll face additional penalties of £10 per day, up to a maximum of £900. After six months, this penalty rises to five per cent of the tax owed or £300, whichever sum is greater.
After a year, an additional charge of 5% or £300 will be imposed – whichever is the greater amount. HMRC stresses that these penalties can be easily avoided by simply submitting your Self Assessment tax return promptly.
Moreover, those who are late in paying their tax will initially have to pay 5% of the unpaid tax at the 30-day mark after it was due. This will then increase by another 5% for being six months and 12 months late, respectively.
HMRC has also highlighted that taxpayers will be charged interest on any outstanding tax they owe.
What if I receive a penalty?
If HMRC issues a penalty for either a late tax return or a late payment, you may be able to avoid paying it if you disagree with the government department’s decision. According to guidance from HMRC, one reason you can disagree with the penalty is if you have a ‘reasonable excuse’.
Typically, you have 30 days from the date a penalty is issued to speak with HMRC and formally make an appeal. If a deadline was missed, you will need to provide a reason for the missed deadline.
How you make the appeal will vary significantly depending on the type of tax you pay and whether you’re employed or self-employed. Full details of this can be found here.
