HMRC Warns of Tax Return Deadline and Penalties

Missing the filing deadline can trigger fines amounting to hundreds of pounds.

The critical deadline for submitting self-assessment tax returns is January 31. Interest also applies to any tax that remains unpaid after this initial cutoff.

Consumer finance expert Martin Lewis is urging immediate action, claiming that 5.6 million people required to file a return have yet to do so.

Myrtle Lloyd, HMRC's chief customer officer, warned that delaying the filing by even a single day will incur costs. HMRC confirmed that anyone who misses the deadline faces an automatic £100 penalty.

Taxpayers who have sold assets since October 2024 must manually calculate Capital Gains Tax adjustments, as the system will not process these changes automatically.

Further penalties apply for long-term non-compliance: after six months, HMRC charges five percent of the tax due or £300, whichever is greater.

Those struggling to pay bills under £30,000 in full may be able to set up a 'Time To Pay' arrangement online. Customers requiring adviser assistance can contact HMRC by phone Monday to Friday, 8am to 6pm.

HMRC reported a 65 percent surge in app usage for Self Assessment payments compared to last year.

For those filing solely to pay the High Income Child Benefit Charge, HMRC says they may be able to pay through their tax code (PAYE) if they make contact before the deadline. HMRC will then amend their code and register them for PAYE payments.

A total of 12 million people are required to file a return. An automatic fixed penalty of £100 is issued for failing to file online, a charge that sits on top of any accrued interest and additional fees.