For services that require prior authorization, where would the authorization number be entered on the CMS-1500 form?

The correct entry for the authorization number on the CMS-1500 form is indeed Block 23. This block is specifically designated for reporting prior authorization numbers or any other necessary numbers related to specific services provided. Including this information in Block 23 is essential for the adjudication of the claim, as it helps the payer confirm that the services rendered were authorized in advance, ensuring compliance with the insurance plan's requirements.

Other blocks on the CMS-1500 form serve different purposes: Block 24A is used for reporting the date(s) of service, Block 20 is for identifying whether the service is related to an employment-related injury or illness, and Block 21 is where the diagnosis or nature of the patient's condition is recorded. Since these other blocks do not pertain directly to prior authorization information, they would not be suitable for entering the authorization number.