Hi Frank,
Thank you for reaching out. It is not possible to get the billing details via Adwords API. Using getBillingAccounts method of Budget Order Service, you can only get the list of all open and active billing accounts and not the selected billing account for a client customer account. Let us know if you have any further concerns.
Regards,
Nikisha Patel, Google Ads API Team
Hi Frank,
With Google Ads API, you could use billing_setup resource or GetBillingSetup method of BillingSetupService to get the approved list of billing set up for an account. At any given instance of time, only one billing set up is active for the specified customer account. Based on the start_date_time and end_date_time of the billing set up, you will be able to retrieve the active billing set up which is currently selected for the client customer account. Let us know if this helps to clarify your concern.
Regards,
Nikisha Patel, Google Ads API Team