After being closed for three months over the summer, HMRC has reopened the self-assessment tax helpline from 4 September.

Between 12 June and 3 September, callers were redirected to digital services to give HMRC time to deal with other phone enquiries and handle the postal backlog.

This was not the first time HMRC has limited access to helplines to reallocate staff elsewhere, but it was the first time the tax authority completely shut down a service for a significant period.

Adam Harper, director of professional standards and policy at the Association of Accounting Technicians, said:

"The need for such a pilot, in order to redirect staff elsewhere, highlights the much bigger challenge that HMRC faces in balancing competing priorities with a constrained budget.

"Ultimately, the Government must address the root problem that more investment is needed."

In June, Victoria Atkins, financial secretary to the Treasury, hinted that the closure of the self-assessment helpline would not be the last, saying:

"We will be watching this very, very carefully. If it is helping with some of the customer service problems we have, then we will look to see if we can surge people at other times of the year when there are peaks and troughs into the higher activity areas"

"It is about using our people as effectively as possible when customers are trying to contact HMRC."

Talk to us about your self-assessment tax return.