Types of Claims 
A claim or request for Medicare payment may be assigned or nonassigned. Regardless of the type of claim, physicians may never charge Medicare patients for completing or filing a claim. Proper completion and submission of a “ clean ” Medicare claim is the first step in accurate claims processing. Clean claims are claims that successfully process without system-generated requests for additional information. 
Assigned Claims

A participating or nonparticipating physician may file an assigned claim. Participating physicians are required to accept assignment for all Medicare claims. A nonparticipating physician is held to the assignment agreement for that claim only and agrees to accept the Medicare fee schedule amount as payment in full for all covered services. The physician is reimbursed directly. To accept assignment of Medicare benefits for a claim, the physician must select the appropriate block (27) of Form CMS- 1500 or the applicable electronic claim field. Physicians may collect reimbursement for excluded services, unmet deductible, and coinsurance, from the beneficiary. Certain services may be paid only on an assigned basis: 
* Clinical diagnostic laboratory services 
* Physician services to individuals dually entitled to Medicare and Medicaid 
* Services of physician assistants, advanced registered nurse practitioners, clinical nurse specialists, nurse midwives, certified registered nurse anesthetists, clinical psychologists, and clinical social workers 
* Ambulatory Surgical Center (ASC) facility charges Home dialysis supplies and equipment paid under Method II 
* All drugs and biologicals covered under Medicare

Nonassigned Claims 
Only a nonparticipating Medicare physician may file non assigned. A nonparticipating physician does not agree to accept Medicare ’ s allowed amount as payment in full and may charge the beneficiary, up to the limiting charge, for the service(s). 
When a nonparticipating physician files a Part B non assigned claim, the beneficiary is reimbursed directly. To refuse assignment of Medicare benefits for a claim, the physician must select the appropriate block (27) of Form CMS-1500 or the applicable electronic claim field.