While most of the payers ask for a copy of W9 form along with a letter with the details including the effective date of the new address, some payers take these info only through their specific form which can be downloaded from their websites. They generally call it Demographics update form or Provider info update form, etc. Some of them are online applications [to make our job easier
]. You should check with the payers' website to be on safer side.
Just in case it is applicable to you, therapists who also supply DME equipments will need to obtain a separate NPI for the 2nd location (if it is going to be an additional location). Good luck.