It is piloting a “seasonal model” for the helpline and anyone who has a query will be redirected to the HMRC digital service. This includes online guidance, a digital assistant, or its webchat service.

HMRC said it’s making the change to “prioritise helping those with urgent queries” and the move will free up 350 advisers to take urgent calls.

It said the vast majority of people who file a self-assessment tax return use online services, and 97% file online.

Between June and August, the phone line receives around 50% fewer calls than in the months between January and April.

The phone line will reopen on 4 September for anyone who has a question or query about self-assessment.

Angela MacDonald, deputy CEO and second permanent secretary at HMRC, said: “ We continually review our services to see how they can best serve the public and we are taking steps to improve them.

“A seasonal SA helpline will make more of our expert advisers available where they are most needed during the summer months.

“Our online services, including the HMRC app, are quick and easy to use and have been significantly improved. I urge customers to explore these fully before deciding to wait to speak to us on the phone.”