When you are setting up a user on your CMS system, you will notice you have a choice between INTERNAL and ACC ASSIGNED (the default is ACC ASSIGNED).
Providers who have an ACC Provider ID should ALWAYS be ticked ACC ASSIGNED.
Admin staff, Cultural Advisors, non ACC provider status Yoga practitioners etc. should be ticked INTERNAL.
When you are doing any kind of billing, the system requires a Provider ID.
If the user/provider is marked as internal, the Provider ID drops off as the Invoicing is submitted to ACC, but is retained within the system for easy tracking and allocation of billables and payments.
If you get an error message on your payments from ACC that says "Provider ID necessary for payment" or similar, check that the provider/user profile is marked as ACC ASSIGNED.