This will be a one time setup for the May 1 billing changes.  Here are the steps to follow to track this down:

(1) Look at the eligibility verification report for the month being billed to get the name of the CA provider;

(2) Make sure you have the correct CA# for that name;

(3) If the CA provider changed, make sure the Billing Extra info reflects the change;

(4) If the patient has multiple CA# make sure the Dr./Pharmacy tab of the referral does not have a CA# entered; 

(5) Make sure you have that CA# cross referenced to the correct NPI.  

If you only have the provider name and not their NPI number or their CA#, you can access individual and group NPI numbers under the NPI Registry @ https://nppes.cms.hhs.gov/NPPES/NPIRegistryHome.do

The CA provider is not a permanent assignment - it can change, but when it does, the change applies to the entire month (and all following months until it changes again)