In which block on the CMS-1500 claim form should the referring provider’s national provider identifier (NPI) be entered?

• A. Block 17b
• B. Block 24A
• C. Block 32
• D. Block 21

Answer: (A)

The key idea is placing the referring provider’s unique identifier in the part of the CMS-1500 that collects information about the physician who referred the patient. The referring provider’s NPI is a 10-digit number that uniquely identifies the physician who initiated the referral, and it must appear in the section of the form reserved for the referring physician’s information. This placement ensures the payer can correctly link the referral to the claim, aiding proper adjudication and care coordination. Other sections of the form are used for the rendering provider, service details, or facility information, so putting the referring NPI in those areas would obscure who originated the referral and could delay processing.