Physician's authorization of NPP's services is a rule you can't miss. CMS recognizes nonphysician practitioners (NPPs) for payment purposes by reimbursing physicians for services provided "incident to" a physician's care. However, CMS has made it clear in 2008's Transmittal 87 that payers will not reimburse these services unless there is documentation authorizing the incident-to service. You could end up dazed and confused if you don't fully understand incident-to rules. But you can't afford not to -- Medicare reimburses at 100 percent of the physician fee schedule when billed incident to, and 85 percent when billed non incident to. Fortunately, you have ways to level up your knowledge about incident-to services. Here are 3 important guidelines. 1. Meet CMS-Set Criteria CMS' Benefit Policy Manual defines "incident to" as "services furnished as an integral although incidental part of a physician's personal professional service." CMS pays NPP office service reported under a physician's NPI at 100 percent, provided you meet these requirements: Important: 2. Upgrade to Latest Requirement Since 2008, CMS has pushed for the physician to document his approval of an NPP to provide follow-up services. Example: The initial physician service in this case is reported as 99203 (with 1.42 RVU) under the physician's NPI, which should get you about $74 in reimbursement when you multiply the RVU withthe current conversion factor of 36.8729. Additionally, you would report follow-up services (e.g., 99213) under the physician's NPI after being provided "incident-to" the physician's plan of care. The NPP should provide evidence of the required physician supervision. You can easily accomplish this through a simple notation in the record, such as "Service performed under the supervision of Dr. Smith." You don't have to present a cosignature for billing purposes, but some payers may require it for licensure issues involving physician assistants. 3. Be Aware of NPP Limitations When a patient comes to the office when no physician is around, the NPP can see and treat her. The NPP can even provide a service within his or her state law guidelines for scope of practice as long as the state's supervision requirements are met. Option: