Four million customers are yet to submit their completed Self Assessment tax return and pay any tax owed ahead of the deadline on 31 January, HM Revenue and Customs (HMRC) has warned.

More than 12.2 million customers are expected to complete a tax return for the 2020/21 tax year.

HMRC is urging the millions of customers still to file their tax return, pay any outstanding liabilities or set up a payment plan, to do so ahead of the deadline as interest will be applied to all outstanding balances from 1 February.

However, earlier this month, HMRC announced they would waive penalties for one month for late filing of tax returns and late payments. The changes mean:

• 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 31 January deadline will not receive a late payment penalty if they pay their tax in full, 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.”

HMRC is offering support to customers completing their tax return. Anyone who is yet to file their return can book a place to access live webinars, running throughout January on GOV.UK. Alternatively, recordings are available on GOV.UK. In addition, HMRC has produced resources to help customers meet their obligations including YouTube videos and Self Assessment guidance on GOV.UK.

There are no changes to HMRC’s Self Assessment helpline opening times. The telephony service will not open on Saturday 29 or Sunday 30 January and will operate as normal until 6pm on Monday 31 January.

The existing Time to Pay service allows any individual or business who needs it the option to spread their tax payments over time. Self Assessment taxpayers with up to £30,000 of tax debt can do this online once they have filed their return.

If customers owe more than £30,000, or need longer to pay, they should call the Self Assessment Payment Helpline on 0300 200 3822.

A full list of the payment methods taxpayers can use to pay their Self Assessment tax bill is available on GOV.UK.

The 2020/21 tax return covers earnings and payments during the pandemic. Taxpayers will need to declare if they received any grants or payments from the COVID-19 support schemes up to 5 April 2021 on their Self Assessment, as these are taxable, including:

• Self-Employment Income Support Scheme
• Coronavirus Job Retention Scheme
• other COVID-19 grants and support payments such as self-isolation payments, local authority grants and those for the Eat Out to Help Out scheme

The £500 one-off payment for working households receiving tax credits should not be reported in Self Assessment.

It is important that customers check and make any changes to their tax return to make sure any SEISS or other COVID-19 support payments have been reported correctly in their Self Assessment.

HMRC urges everyone to be alert if they are contacted out of the blue by someone asking for money or personal information. Taxpayers should always type in the full online address www.gov.uk/hmrc to get the correct link for filing their Self Assessment return online securely and free of charge. HMRC sees high numbers of fraudsters emailing, calling or texting people claiming to be from the department. If in doubt, HMRC advises not to reply directly to anything suspicious, but to contact them straight away and to search GOV.UK for ‘HMRC scams’.