Which two coding systems are typically used in Medicare billing to classify services and diagnoses?

• A. CPT for procedures, ICD-10-CM for diagnoses.
• B. CPT for diagnoses, ICD-10-CM for services.
• C. CPT for payer requirements, ICD-10-CM for patient demographics.
• D. CPT for billing cycles, ICD-10-CM for privacy.

Answer: (A)

In Medicare billing, the service or procedure performed is described with CPT codes, while the patient’s diagnosed condition is captured with ICD-10-CM codes. This pairing shows what was done (CPT) and why it was done (ICD-10-CM), which supports medical necessity and proper reimbursement. CPT focuses on procedures and services, whereas ICD-10-CM identifies diagnoses that justify those services. Other options mix roles that CPT and ICD-10-CM are not intended for, such as using CPT for diagnoses or using either code set for payer rules, demographics, or privacy.