Four million individuals are still yet to submit their completed self-assessment tax return and pay any tax they owe ahead of the deadline on 31 January, HMRC has warned.

The tax authority is urging the millions of customers still to file to pay any outstanding liabilities or set up a payment plan before interest is applied to all outstanding balances from 1 February.

Earlier this month, HMRC said anyone who cannot file their return by the 31 January deadline will not receive a late filing penalty if they file by 28 February.

Anyone who cannot pay their tax liabilities by the same deadline will not receive a penalty if they pay their tax, or set up a time to pay arrangement, by 1 April.

Myrtle Lloyd, HMRC's director general for customer services, said:

"We know some customers may struggle to meet the self-assessment deadline on 31 January which is why we have waived penalties for one month, giving them extra time to meet their obligations.

"And if anyone is worried about paying their tax bill, they can set up a monthly payment plan online - search ‘pay my self assessment' on GOV.UK."

Talk to us about your self-assessment.