Be sure to submit the correct form to prevent any delays. An assignment agreement is between a supplier of services and a Medicare beneficiary.The option of accepting assignment belongs solely to the supplier. Step 1: Follow the instructions in this packet to fill out the necessary forms. Use this form if you receive a surprise bill for health care services and want the services to be treated as in network. Such compensation shall continue until the assignment is ended by: 1. The incumbent's return; or. 2. Take this form with you to the hearing.