HMRC Issues Final Reminder to Register for Self Assessment to Avoid £100 Penalty

HM Revenue & Customs (HMRC) has issued a final reminder for UK residents to register for Self Assessment by the deadline of Monday, 5 October, to avoid a £100 penalty.

The tax authority has reminded the public that failing to register on time will lead to an automatic fixed penalty of £100, with additional daily fines of £10 per day for up to 90 days.

In a post on X, HMRC stated: “ALERT: Today is the deadline to register for Self Assessment. Use our online tool to find out if you need to complete a tax return, and register today. Failure to do so could lead to penalties. Act now.”

Self Assessment is the system used for collecting Income Tax from individuals whose tax is not automatically deducted from their income. This generally includes the self-employed, landlords, high earners, and investors.

HMRC advises the public to use their online tool to check if they need to submit a tax return for the 2025 to 2026 tax year (6 April 2025 to 5 April 2026). The tool does not submit any information to HMRC.

Those who receive a letter from HMRC requiring a tax return must comply by the deadline stated in the communication.

Penalties increase the longer a return is late. Filing one day late results in a £100 fixed penalty. After that, a daily charge of £10 applies for up to 90 days.

If the tax payment is six months late, a further penalty of 5% of the tax owed or £300, whichever is greater, will be imposed. An additional 5% or £300 penalty applies if payment is late by 12 months.

Tax Aid has advised that if individuals receive a request to complete a tax return but believe they are not required to, they can ask HMRC to withdraw the return. HMRC may do so if it agrees the request was made in error and the individual has no income to report.

However, if the individual had income, even if no tax is due – such as making a loss in business – they are still required to complete the return.