Which block on the CMS-1500 claim form is designated for billing ICD codes?

The correct block for billing ICD (International Classification of Diseases) codes on the CMS-1500 claim form is Block 21. This block is specifically designated for entering the diagnosis codes that represent the patient's medical condition. When submitting claims for reimbursement, it is essential to accurately fill this block, as it provides the necessary information for insurance companies to understand the reasons for the services provided.

Understanding the use of Block 21 is crucial for billing and coding specialists because it directly influences the processing of claims and the reimbursement process. Accurate coding in this block ensures that the medical necessity of the services is properly communicated to the payer, which is key in avoiding denials and ensuring prompt payment.