Submitting a secondary claim to Medicaid using the CMS-1500 form requires careful attention to specific fields and documentation to ensure timely reimbursement. Medicaid acts as the payer of last resort, so claims must first be processed by the primary insurer before submission.
1. When to File a Secondary Claim
Medicaid secondary claims are filed only after primary payers, such as Medicare or private insurers, have processed the claim. According to the Medicare Secondary Payer Manual, if multiple primary payers are involved, the claim must be submitted on paper CMS-1500 forms along with all original Explanation of Benefits (EOBs).
For comprehensive rules and requirements, see our internal article on Secondary Claim Submission CMS-1500 Requirements.
2. Key CMS-1500 Fields for Secondary Claims
2.1 Item 9: Other Insured’s Name & Relationship
This field should include the name of the primary insured and their relationship to the patient. For Medicare beneficiaries, this is often “self.” Correct entry here ensures proper coordination of benefits.
See our detailed walkthrough of CMS-1500 forms: CMS-1500 Claim Form Instructions.
2.2 Item 11: Insured’s Policy Information
- 11a: Date of birth and sex of the insured
- 11b: Name of the primary insurer
- 11c: Policy or group number
- 11d: Address or Payer ID of the primary insurer
Accurate completion of these fields helps Medicaid identify the primary payer and prevents claim rejections. Also, remember to use appropriate two-digit qualifiers in other form fields.
2.3 Item 29: Amount Paid
- 29a: Total charge for each service
- 29b: Amount paid by the primary insurer (exactly as it appears on the EOB)
- 29c: Balance due (the difference between 29a and 29b)
Precise data in this section prevents “force-balance” denials. Learn more at Box 29: Amount Paid – Secondary Claim Field.
Suggested image here: Annotated CMS-1500 form highlighting Items 9, 11, and 29.
3. Required Attachments
- Attach a complete copy of the primary payer’s EOB or remittance advice. This is mandatory for Medicaid secondary claims.
- Include medical records if requested by Medicaid to support the services billed.
For Medicare crossover claims, review our guide on CMS-1500 Medicare EOMB Requirements.
4. Modifiers & Resubmission Codes
- When resubmitting corrected claims, use the appropriate codes in Box 22 to indicate the reason. Our Box 22 Resubmission Codes Explained article offers detailed instructions.
- While modifiers such as -OA or -OB are less common on CMS-1500 secondary claims, be mindful of NCCI edits to avoid bundling issues. For additional details, see the CMS Coordination of Benefits Guidelines.
5. Electronic vs. Paper Submission
Most Medicaid secondary claims with multiple primary payers must be submitted on paper using the CMS-1500 form to attach all necessary EOBs. While electronic 837P submissions are common, paper submission is often required for coordination of benefits cases. For proper formatting, review our Sample New CMS-1500 Claim Form.
6. Tips to Avoid Denials
- Match EOB Amounts Exactly: Any discrepancies between Item 29b and the EOB lead to denials.
- Use Consistent Date Formats: Follow proper date formatting in Items 3, 9b, and 11a.
- Check State Medicaid Rules: Coordination of benefits policies vary by state; confirm local requirements.
- Follow Up Promptly: Document denial codes and resubmit claims quickly with corrections and attachments.