Use this simple checklist from Astrid Medical Services to see whether your referring physicians are in PECOS. 1. Download the physician file at www.cms.gov/MedicareProviderSupEnroll/Downloads/OrderingReferringFile_CSV.zip 2. Unzip the file. 3. Change the extension from .csv to .txt. 4. Double click the file and it should open in Notepad. Key Control F, or click Edit>Find. 5. Enter the NPI number and confirm the physician's name.