Which block should the billing and coding specialist complete on the CMS-1500 claim form for a secondary insurance company?

In the CMS-1500 claim form, the correct block to complete for a secondary insurance company is block 9a, which is designated for the "Other Insured's Policy or Group Number." This block is specifically intended to capture the details of the secondary insurance coverage. When a patient has multiple insurance policies, it's important to indicate the primary and secondary policies correctly to ensure proper claims processing and payment.

Filling out block 9a allows the billing and coding specialist to provide the insurance company with the relevant information about the secondary policy, which assists in coordinating benefits between the two insurers. This coordination is essential for accurately determining the amount that is owed by each insurance provider and ensuring that the patient is billed correctly for any remaining balance.

Block 9 itself collects information about other insured parties but does not specifically address the need for policy or group number details that are critical for processing claims with secondary insurances. Block 10 pertains to the patient's condition related to employment or other non-insured status, and block 11 is used for listing the insured's information, which would not specifically relate to the secondary insurer's policy details. Therefore, block 9a is the most appropriate choice for the billing and coding specialist to complete for a secondary insurance company.