CMS-1500

The CMS-1500 (formerly HCFA-1500) is the standard claim form used to bill professional medical services to Medicare, Medicaid, and most commercial insurance payers. It is the form completed for any service provided in a physician office, outpatient setting, or by individual practitioners. The electronic equivalent is the 837P (Professional) transaction, which is the version actually transmitted in 99%+ of submissions today through clearinghouses. The form contains 33 numbered boxes capturing patient demographics, insurance information, referring/rendering/billing provider NPIs, diagnosis codes (ICD-10), procedure codes (CPT/HCPCS), modifiers, dates of service, place of service, charges, and prior authorization references. Common CMS-1500 errors that trigger CO-16 denials include missing or invalid rendering provider NPI, missing taxonomy code, mismatched place-of-service code, missing CLIA number on lab claims, missing NDC on physician-administered drug claims, and missing referring provider NPI on services that require referral. Institutional services (hospital inpatient, outpatient facility, ambulatory surgery centers) bill using the UB-04 (837I) form instead. Both forms feed the same downstream adjudication process, but the data fields and box numbers differ significantly.