How to Fill Out the CMS-1500 (HCFA 1500) Form Correctly in 2025

Submitting clean claims is crucial to keeping healthcare reimbursements timely and error-free. One of the most important tools in this process is the CMS-1500 form, used by individual healthcare providers to bill insurance companies for services rendered. In fact, filling out the CMS-1500 (formerly HCFA 1500) form might seem like a routine task. But it is a critical step that can make or break your revenue cycle in the world of medical billing. Even a small mistake like an incorrect date format or a missing code can lead to payment delays or denials.

In this blog, we break down the form box by box, explain the differences between CMS-1500 and HCFA-1500, and highlight common mistakes to avoid so you can get it right the first time, every time.

What is the CMS 1500 Form?

The CMS-1500 form is a standardized medical claim form used by non-institutional healthcare providers to bill insurance companies, including Medicare and Medicaid. This form allows physicians, nurses, clinical staff, ambulance services, and other individual providers to request reimbursement for medical services rendered to patients. It is issued by the Centers for Medicare & Medicaid Services and ensures that all necessary patient and service information is captured in a uniform format for easier processing by insurers. In fact, the accurate completion of the CMS-1500 form helps avoid delays, claim denials, and payment errors.

CMS 1500 vs HCFA 1500 Forms

The CMS-1500 form is the current version of the standardized claim form previously known as the HCFA-1500. The HCFA-1500 form was initially developed by the Health Care Financing Administration, which was later renamed CMS. Although both forms serve the same purpose, i.e., claiming payment for outpatient and non-hospital services, the CMS-1500 has replaced the HCFA-1500 form. In fact, the CMS-1500 includes updated fields to meet new regulatory standards, such as the use of ICD-10 codes. Thereby, providers should only use the CMS-1500 form as the HCFA version is outdated and no longer accepted by most insurance companies.

Step-by-Step Guide to Fill Out the CMS-1500 (HCFA 1500) Form Correctly in 2025

Completing the CMS-1500 form accurately and clearly helps ensure that insurance claims are processed quickly and without errors. One should always refer to the latest CMS updates and payer-specific guidelines to stay compliant in 2025. The following is a simple step-by-step breakdown of what to enter in each section of the form-

Section 1 - 13: Patient and Insurance Information

These boxes collect basic details about the patient and their insurance coverage.

• Box 1: Choose the insurance type (Medicare, Medicaid, etc.) based on the patient's plan.
• Box 1A: Enter the patient’s insurance ID number (usually found on the insurance card).
• Box 2: Write the patient’s full legal name as it appears on their Medicare or insurance card.
• Box 3: Add the patient’s birth date and select their gender.
• Box 4: Fill in the insured person's name only if it’s different from the patient (e.g., parent or spouse).
• Box 5: Enter the patient’s full address and phone number.
• Box 6: Indicate the relationship of the patient to the insured (self, spouse, child, etc.).
• Box 7: Provide the insured person’s address (if different).
• Box 8: Leave this box blank (reserved for NUCC use).
• Box 9 - 9D: Use this section if the patient has secondary insurance. Enter all relevant policy and insured information.
• Box 10: Check the appropriate boxes to indicate if the service was due to a work, auto, or other accident.
• Box 11: Enter the group or policy number of the insured, plus birth date and gender if not already listed. If you used box 9, check "Yes" in Box 11d.
• Box 12: Patient’s or authorized person’s signature and date to release medical information.
• Box 13: Signature for allowing payment of benefits to the provider.

Section 14 - 20: Service and Treatment Information

These fields are used to describe the treatment and diagnosis.

• Box 14: Date of current illness or injury.
• Box 15: Other related dates (optional based on case).
• Box 16: Dates the patient was unable to work due to condition (if applicable).
• Box 17 - 17b: Name and NPI of referring physician or provider.
• Box 18 - 20: Hospitalization dates related to current services, if any. Also, indicate if the diagnosis is related to employment, an auto accident, or another accident.

Box 21: Diagnosis or Nature of Illness or Injury

Use this box to list the ICD-10 diagnosis codes in priority order. Moreover, enter the ICD indicator (0 for ICD-10) to confirm which code set is being used.

Box 22: Medicaid Resubmission

You should enter the original Medicaid claim reference number if you are resubmitting a corrected or denied claim.

Box 23: Authorization Number

Use this box to include the prior authorization number provided by the insurance company, if required for the visit or procedure.

Box 24: Service Line Details

Fill these boxes carefully for each service performed-

• Box 24A: Service dates (in MM/DD/YY or MMDDCCYY format).
• Box 24B: Place of service code (like 11 for office, 21 for inpatient).
• Box 24D: CPT/HCPCS codes and any modifiers for services performed.
• Box 24E: Diagnosis pointer(s) that link the procedure to the diagnosis in Box 21.
• Box 24F - 24G: Charges and units (number of times the service was provided).
• Box 24J: Enter the provider’s NPI. Leave 24C, 24H, and 24I blank unless required.

Box 25 - 30: Billing and Claim Information

These boxes are used to fill in the details related to medical billing and claims:

• Box 25: Provider’s Tax ID or Social Security Number.
• Box 26: Patient’s account number for internal use.
• Box 27: Indicate if the provider accepts assignment of benefits.
• Box 28: Total charges for the services provided.
• Box 29: Amount paid by the patient or other insurance.
• Box 30: Leave this box blank (not used).

Box 31: Provider Signature

This box requires the signature of the physician or supplier and the date the form is signed.

Box 32: Service Facility Location

Use this box to enter the address and NPI of the facility where the services were actually provided (e.g., clinic location). If it is the same as Box 33, you may leave this blank.

Box 33: Billing Provider Information

This section is used to write the billing provider’s name, address, and NPI. This is where payment will be sent.

Common Mistakes to Avoid When Filling Out the CMS-1500 Form

Carefully reviewing the form before submission can significantly reduce the chances of rejection and help streamline your medical billing process. To prevent claim denials or processing delays, it is important to avoid these common mistakes when completing the CMS-1500 form

• Using the Wrong Ink Color: Always use black ink only. Any other color may result in the form being rejected by scanners.
• Highlighting Text: Do not highlight any part of the form or its attachments. Highlighted areas may not be readable by automated systems.
• Making Manual Corrections: Avoid using correction fluid, scratching out, or rewriting information on the form. Submit a new form if errors occur.
• Using Special Characters: Do not use symbols like dollar signs ($), commas (,), or decimals (.): for example, write "1000" instead of "$1,000.00".
• Attaching Staples or Stickers: Do not staple, tape, or attach any stickers to the form. These can interfere with scanning equipment.
• Leaving Out Required Information: Double-check that all mandatory fields are filled in correctly, including patient and provider details, codes, and service dates.
• Forgetting Signatures: Make sure to include all required signatures, especially in Box 12 and Box 31, to authorize claim release and certify accuracy.

Conclusion

Completing the CMS-1500 form correctly is a critical part of ensuring a healthy and uninterrupted revenue flow in any healthcare practice. Every detail, such as patient information, diagnosis codes, service dates, and provider identifiers, must be entered with precision to avoid costly claim rejections or delays. As insurance regulations evolve, staying compliant and up-to-date with formatting rules and payer-specific requirements becomes more challenging.

To save time and reduce errors, many healthcare providers are choosing to outsource CMS-1500 form submissions to reliable medical billing experts. 24/7 Medical Billing Services offers specialized support for filling out and submitting CMS-1500 forms accurately and efficiently. With experienced professionals, up-to-date coding knowledge, and robust claim tracking systems, they help streamline your revenue cycle and improve your financial performance.

FAQs

Q1. Can CMS-1500 forms be submitted electronically?

Providers can submit them electronically via the 837P format.

Q2. Where can I get the official CMS-1500 form?

It is available through authorized suppliers and should be printed in red OCR format.

Q3. Are handwritten CMS-1500 forms accepted?

Handwritten forms are discouraged rather than typed entries are preferred for clarity.

Q4. Can dental providers use the CMS-1500 form?

Only for procedures covered under medical insurance, not routine dental.