What should be entered in Block 17 A?

• A. Referring physician's NPI number
• B. Leave blank
• C. Patient's ID number
• D. Provider's office address

Answer: (B)

Block 17 A of the CMS-1500 form is designated for the referring physician’s NPI (National Provider Identifier) number when applicable. However, if there is no referring physician for the services rendered, Block 17 A should be left blank.

Leaving this block unfilled is appropriate when the patient's care does not involve a referring physician, which is sometimes the case, especially in certain direct-access situations or when the patient is visiting a specialist without a prior referral. Understanding when to leave this block blank is crucial to ensure that the claim is processed correctly and doesn't face delays due to unnecessary information being submitted.