reciprocal billing for inpatient services

I am unable to clarify what CMS requirments are for reciprocal billing for inpatient services.

If a physician outside of the on-call or regular attending physician's group sees a patient under a reciprocity agreement, who bills? The out-side physician or, the regular attending physician?

If the physican's are both in the same group, does any money change hands, or, does the physician who actually sees the patient do so at no charge and the regular attending physician bill?

I understand the outpatient side - I can't find anything relating to inpatient. Need help ASAP please!

Carole

re: reciprocal billing for inpatient services

Under reciprocal billing arrangements, a patient's regular physician may submit a claim and receive payment for the services arranged to be provided by a substitute physician on an occasional basis. The regular physician should identify the service as substitute physician services and bill with the Q5 modifier (service furnished by a substitute physician under a reciprocal billing arrangement). This pertains to inpatient services.
https://www.cms.gov/transmittals/downloads/R1728B3.pdf
Make sure it is a reciprocal arrangement.