Hi Federica Buso,
Thank you for your query
We apologise for the current wait times on the phone lines, during this busy time of year we are receiving a high volume of calls, we are currently trying our best to reduce the long wait times, the quietest time of day for contacting the helpline is the first and last hour the lines are open, between 8-9am and 5-6pm.
However if you are unable to call at these times, an alternative to contacting us via telephone is our customer webchat. Please find the link below:
Ask HMRC online -
Ask HMRC - GOV.UK
Thank you.