HMRC have insisted that "no-one will be unfairly penalised" as a result of its decision to delay sending out penalty notices to taxpayers who missed January's self-assessment deadline. 

The Revenue said an increased workload from Brexit had prompted a decision to send the letters which usually go out in February, later. The latest the letters will go out is the end of April and so when the letters arrive, penalties could already be accruing. From 1st May the standard £100 fine rises by £10 a day.

It is thought that 746,000 taxpayers missed the submission deadline in January. An HMRC spokesman said "the vast majority will be aware they missed the filing date, as we do remind regularly before the deadline. The latest date letters will go out is April and this will still leave customers several weeks to contact us".