If any of your employees need to contact HMRC the correct details for Income Tax, Pay As You Are Earn and Self Assessment are:
HM Revenue and Customs
The telephone number is 03000 200 3300.
They will need to have their National Insurance number to hand when contacting HMRC.
Employees can set up or sign into their personal tax account where they can check and update their records at www.gov.uk/personal-tax-account.