Most of the time especially for the big insurances example BCBS etc, they require 1 mailing/billing address per 1 tax id. Medicare is the same as well. 1 ptan# for 1 tax id.
Just the same, its always best to get it from the insurances themselves. But this is what I have gone thru so far after adding a second location to one of our clients.
Also, when adding a second location, there is no need for another contract unless for medicare its another pay locality, in which will require a new PTAN #.
You will need to inform the payers that you are adding a second location.
Hope this information helps.