Your practice may or may not bill Medicare for your services.
However, for us as pathologists to be able to bill Medicare, you need to enroll in PECOS which stands for Medicare Provider Enrollment, Chain, and Ownership System. It is a database where healthcare providers register with the Centers for Medicare and Medicare Services (CMS). CMS developed PECOS because of the Patient Protection and Affordable Care Act.
Your enrollment in PECOS does not mean that you must take Medicare patients—it ensures that Medicare will reimburse us for a histopathological diagnosis when you perform a biopsy on a patient with this type of insurance. Currently, because you are not enrolled, we do not get any reimbursement from Medicare for our service, and we cannot bill the patient.
Another option is for you to opt-out of Medicare. If you opt out, you will be able to order services for Medicare beneficiaries. Your opt-out information must be current (an affidavit must be completed every two years, and the NPI is required on the affidavit). Opt-out practitioners whose affidavits are current should have enrollment records in PECOS that contain their NPIs.
We do not anticipate the enrollment or opt-out process to take more than one hour. If you need help at any time while completing the application, please do not hesitate to contact us: Wendy: 1-800-358-1011, [email protected]

link for additional information: https://pecos.cms.hhs.gov/pecos/login.do#headingL