For six weeks between 17 April and 2 June, the Agent Dedicated Line (ADL) will only deal with calls relating to self assessment late filling penalties and appeals, and PAYE coding enquiries.

For all other enquiries tax agents and accountants will have to use online services or the main helplines.  

HMRC said that calls would be answered on the general helplines but it could take ‘longer than usual’.

The agent dedicated line will not answer any progress chasing calls so as to prioritise the ‘best possible service to all customers at one of our busiest times’.

Richard West, director of personal tax operations at HMRC, said: ‘To make sure we can give the best possible service to all customers at one of our busiest times, we’re making a temporary change to our Agent Dedicated Line.

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