Symptoms
I want to set (or change existing) Tax Zone to a certain value for all existing customers. Can it be done automatically without changing of Tax Zone for each customer separately?
Resolution
There is no such functionality in current implementation of PBA-E. It should be possible to use AccountUpdate_API for Tax Zone update, but due to bug PBA-10947 the API can not be used either.
Currently the only way is to set Tax Zone separately for each customer.