You will need all the details you used to set up the services you are moving such as tax reference numbers and postcodes.
To move your online services into one account please follow these steps:
Log in with the User ID for the online service you want to move, remove (de-enrol) the service(s) then log out of this account.
Log in again, this time with the User ID and password you want to use as your main account. On the 'Your HMRC services' page you will see a list of services you can add.
Select the service(s) you have just removed and enrol for them again, following the on-screen instructions.
If the service you've added needs to be activated before you can use it HM Revenue and Customs will send a new activation code to the address held for you.
When you have successfully moved your services, you will be able to see them on the 'Your HMRC services' page of your chosen account.