Taxpayers have been given longer to avoid a £100 fine for filing their self assessment return late, because of a strike by HM Revenue and Customs (HMRC) staff.

The walkout on 31 January, which is the deadline to file an online return, means those who phone HMRC for help on the day may be unable to get through.

As a result, HMRC says it will not issue penalties to anyone who files their return on 1 or 2 February. Equally, those with tax to pay by the 31 January deadline will not face any interest on payments made on 1 or 2 February.

Exchequer secretary to the Treasury David Gauke says: "This strike could have caused thousands of people to incur fines, so I am pleased that HMRC has taken this common-sense approach.

"The Government does not want anyone trying to file their tax return on time to be unfairly penalised because they were unable to get through for help and advice on 31 January."

The big change to the rules this year is anyone late will be fined £100, though they now have two days' grace.

In past years, you were only fined if you were late AND owed tax, meaning you could make a payment to avoid the fine (see the Self assessment tax fine MSE news story).

If you owe tax, you will be charged 3% annual interest on late payments.

Up to 20,000 members of the Public and Commercial Services union (PCS) working in call centres and enquiry offices took strike action last week in a row over the appointment of private companies to run call-handling trials in two contact centres, and will walk out for 24 hours next Tuesday.