What is the purpose of Block 25 on the CMS-1500 form?

• A. To record the Federal Tax ID Number.
• B. The patient's insurance policy number.
• C. The diagnosis code.
• D. The provider's NPI.

Answer: (A)

Block 25 collects the Federal Tax Identification Number of the billing provider or organization submitting the claim. This identifier is used by payers for tax reporting and to link the claim to the correct legal entity, helping ensure payments are issued to the right business and reported properly to the IRS. It’s a tax-identity detail, not the patient’s policy number, nor the diagnosis code, and it’s separate from the provider’s NPI, which is stored in a different field.