The head of a powerful committee of MPs has raised concerns about a decision to close off the main self-assessment helpline over the summer.

HM Revenue & Customs (HMRC) announced last week that it will pilot a new “seasonal model” for the helpline, to help free up advisers to answer urgent calls on other lines and answer customer correspondence.

HMRC will trial directing self-assessment queries from the helpline to the department’s digital services, including its online guidance, digital assistant and webchat.

The helpline will reopen on September 4 2023 so people can receive expert support in the five months leading up to the self-assessment deadline on January 31 2024.

Harriett Baldwin, chairwoman of the Treasury Committee, has written to HMRC to ask several questions, including whether the move has been prompted by staffing issues in the department, or backlogs or issues in other areas.

She has also asked whether the closure of the helpline is related to HMRC’s homeworking policy, as well as what contingency arrangements are in place should taxpayer detriment be greater than expected during the trial.

HMRC has previously said that the self-assessment helpline receives far fewer calls over the summer, with calls around 50% higher between January and April compared with June to August.

Commenting on the correspondence, Ms Baldwin said: “Given the potentially significant impact closing the self-assessment helpline may have on taxpayers, we’re looking for clarification that HMRC has fully considered the costs and benefits of this decision.

“There are also concerns around the short notice with which this was announced. HMRC must be open, upfront and transparent when making decisions which could impact so many individuals.”

An HMRC spokesman said: “We continually review our services and a seasonal SA (self-assessment) helpline will make more of our expert advisers available to respond to the most urgent queries over the summer.

“The change will ensure more customers who really need to speak to an adviser can do so, and we’ll closely monitor the trial.

“Our online services, including the HMRC app, are quick and easy to use and have been significantly improved.”