All calls to the helpline will be redirected to digital services over the period to give HMRC time to deal with other more urgent phone enquiries.
The helpline will be closed for three months from Monday 12 June until Monday 4 September.
During this time HMRC said it will 'trial directing self assessment queries from the helpline to the department's digital services, including its online guidance, digital assistant and webchat'.
HMRC will increase the number of advisers available on webchat, the online service helpline and the extra support team helpline.
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.' We are experienced in self assessment matters and dealing with HMRC.