Which of the following is NOT included in Block 33 of the CMS-1500 form?

Block 33 of the CMS-1500 form is specifically designated for the billing provider's information. This block typically includes the billing provider's name, their address, and their telephone number. Each of these elements is essential for ensuring that payment is directed correctly and that the insurance company can contact the provider if needed.

Diagnosis codes, on the other hand, are recorded in specific blocks designated for that purpose, particularly in Blocks 21 and 24. These codes provide details about the medical condition being treated and are crucial for claim processing, but they are not found in Block 33. Therefore, the absence of diagnosis codes in Block 33 is what makes it the correct answer in this context.