Understanding CMS 1500 Box 31 and Box 33: A Comprehensive Guide

The CMS 1500 form, also known as the Health Insurance Claim Form, is a crucial document used for submitting healthcare claims. Within this form, specific boxes hold essential information for accurate processing and reimbursement. In this comprehensive guide, we will delve into CMS 1500 Box 31 and Box 33, exploring their significance and providing detailed instructions on completing them correctly.

Section 1: Understanding CMS 1500 Box 31

What is CMS 1500 Box 31?

CMS 1500 Box 31 is an important section of the claim form that captures the "Signature of Physician or Supplier" [[3]. It serves as a legal attestation and signifies the provider's responsibility for the accuracy and validity of the claim. The signature certifies that the services rendered were necessary and billed appropriately.

Guidelines for Completing CMS 1500 Box 31

When completing CMS 1500 Box 31, it is crucial to follow these guidelines:

1. Use blue or black ink: 

To ensure legibility, use either blue or black ink when signing within Box 31.

2. Legible signature:

 Sign your full legal name clearly within the designated space. Avoid using initials or illegible signatures.

3. Authorized signatures: 

authorized individuals, such as the rendering provider or supplier, should sign within this box.

4. Electronic signatures:

 If submitting claims electronically, CMS requires an equivalent electronic signature method compliant with HIPAA standards.

Section 2: Understanding CMS 1500 Box 33

What is CMS 1500 Box 33?

CMS 1500 Box 33 is where the "Billing Provider Info & Phone Number" is recorded [[3]. It captures essential information about the billing provider, facilitating communication and identification during the claims process.

Guidelines for Completing CMS 1500 Box 33

To accurately complete CMS 1500 Box 33, keep the following guidelines in mind:

1. Billing provider information: 

Enter the billing provider's name, address, city, state, and ZIP code within the designated spaces. Ensure the information matches the provider's enrollment records.

2. Telephone number: 

Include the telephone number where the billing provider can be reached for inquiries or additional information regarding the claim.

3. NPI and Tax ID: 

Ensure the National Provider Identifier (NPI) and Tax Identification Number (TIN) associated with the billing provider are accurate and up to date.

Section 3: FAQs about CMS 1500 Box 31 and Box 33

Frequently Asked Questions (FAQs)

1. Can a claim be processed without a signature in CMS 1500 Box 31?

No, a claim submitted without a valid signature in CMS 1500 Box 31 may be considered incomplete and could result in processing delays or claim denials. The signature is a legal requirement to verify the accuracy and authenticity of the services provided.

2. Can I use an electronic signature in CMS 1500 Box 31?

Yes, CMS allows the use of electronic signatures for claims submitted electronically. However, it is essential to adhere to the electronic signature standards outlined by HIPAA and CMS.

3. What if there are multiple rendering providers on the claim?

If there are multiple rendering providers involved in a claim, each provider must sign CMS 1500 Box 31 individually, certifying the services they rendered. Make sure to include the appropriate signatures for each provider involved in the care.


In conclusion, understanding CMS 1500 Box 31 and Box 33 is crucial for accurate claim submission and efficient reimbursement. Box 31 requires a valid signature from the rendering provider, certifying the accuracy of the services rendered. On the other hand, Box 33 captures the billing provider's information, facilitating communication and identification during the claims process.

By following the guidelines provided in this comprehensive guide, healthcare providers can ensure compliance with CMS requirements, reduce claim processing delays, and increase the likelihood of successful reimbursement.

Remember, accurate completion of CMS 1500 Box 31 and Box 33 contributes to seamless claims processing and helps healthcare providers deliver quality care to their patients.

Disclaimer: This article is for informational purposes only and does not constitute legal advice. It is recommended to refer to the official CMS guidelines and consult with legal and billing professionals for specific case-related questions or concerns.


- [3] CMS-1500 Claim Form Instructions - JD DME - Noridian. Retrieved from