Medicare as Secondary Payer

Yes. Unless you have been approved to submit hard copy claims to Medicare, submit all Medicare claims electronically, including Medicare Secondary Payer (MSP) claims. An exception to this requirement is when a patient has two or more payers who are primary to Medicare. In situations where Medicare is the tertiary payer, these claims may be submitted hard copy.

The ASC v5010 format allows for electronic submission of primary payer information for MSP claims. Palmetto GBA also offers the PC-ACE Pro32 EDI billing software, which supports electronic submission of MSP claims.

Last Reviewed: 03/23/2026

MSP refers to when Medicare doesn’t have primary responsibility for paying the medical expenses of a Medicare beneficiary. The Medicare beneficiary uses other coverage that pays the primary health benefits. MSP claims can be submitted electronically.

Palmetto GBA has rejected some claims because the MSP type submitted on the claim doesn’t match the patient's Medicare record. Review these examples of situations when you receive these Medicare rejections:

• Do you routinely submit claims with an MSP type that Medicare doesn’t list as valid for that patient?
• Is your patient covered by Medicare as an Aged Worker, but their claims are being submitted as Disability?
• Was your patient's injury related to Workers' Compensation (WC), but their claim was submitted as an Aged Worker?
• If you submit claims through an electronic clearinghouse, give them the correct MSP type for each claim. If Medicare is still rejecting your claims, verify that your clearinghouse is submitting the MSP type you provided for each patient.

If you answered "Yes" to any of the above, your Medicare MSP claims are likely rejecting due to a mismatch. This situation can drastically impact your office’s cash flow. Here are the loops and segments where this information is in the electronic claims format:

• Always submit the appropriate MSP type for the beneficiary's insurance coverage
• If the submitted MSP type doesn’t correspond to the information Medicare has on file, your claim will be rejected. Submit rejected claims as new claims.

Here are the valid MSP types that may be submitted on electronic claims.

Last Reviewed: 07/20/2026

No. The EDI fax process can only be used to submit supporting documentation (e.g., office notes, operative reports, patient history and physical, or other medical records) with initial electronic claim submissions. However, the 5010 format does allow for electronic submission of primary payer information for MSP claims. Palmetto GBA also offers the PC-ACE Pro32 EDI billing software, which supports electronic submission of MSP claims.

Last Reviewed: 03/23/2026

There are times when a provider will receive a primary payment from another insurance company after Medicare has paid as primary. When this happens, it is assumed that Medicare should be the secondary payer. If you receive two primary payments, you should refund Medicare’s payment in full.

• Refund the Medicare payment to Palmetto GBA within 60 days of the date you identify the overpayment, even if Medicare’s records show that Medicare is primary
  • Send a copy of the other insurer’s Explanation of Benefits (EOB) and the Overpayment Refund form with your check. The Overpayment Refund Form is available on our website under Forms tab at the top of the web page.
  • If you send a refund without the primary insurer’s EOB, Palmetto GBA may apply the refund to any other accounts receivable for that provider or provider group
  • After Palmetto GBA processes and applies your refund, you may resubmit the claim as a Medicare Secondary Payer claim
  • After 30 days, you may call the provider contact center (PCC) to verify the refunded status. Note: The Interactive Voice Response (IVR) System will not specify that the claim was refunded. The status will reflect processed and paid.
• Although we will deposit your check almost immediately, it may take as long as 30 days for the status of the claim to show a refund status. Please do not resubmit your claim before we have applied the refund to the original claim, otherwise the new claim will deny as a duplicate.
• Remember, you can obtain claim status information through the IVR at any time
• If Medicare records show that Medicare is primary for the patient, Palmetto GBA will request that these records (Common Working File [CWF] records) be updated to reflect that Medicare is secondary. The MSP Contractor will update the records.
  • Please note that updates to CWF records can take up to 100 days
  • To avoid additional overpayments while Medicare’s records are being updated, file all subsequent claims for that patient with the payment information (EOB) from the primary insurer
• A good resource for understanding when Medicare pays primary or secondary is available on the Palmetto GBA website. Refer to the MSP Lookup Tool.

Reference: CMS IOM Publication 100-05, Chapter 3, Section 10.4 (PDF).

Last Reviewed: 03/23/2026

Last Reviewed: 03/23/2026

The timely filing requirement for primary or secondary claims is one calendar year (12 months) from the date of service. Providers should follow up with primary insurers if there is a delay in processing that may result in going past the Medicare timely filing limit.

Last Reviewed: 03/23/2026

If you have submitted a claim and received a denial indicating that the claim is related to a no-fault or WC case, you can submit an appeal explaining that the services are non-related.

Last Reviewed: 03/23/2026

There are two reasons your claim may have rejected. You must correct and resubmit the rejected claim with valid and necessary information for adjudication of your claim.

Reviewing the issues below will assist in resolving rejections with Remark Code MA04: "Secondary payment cannot be considered without the identity of or payment information from the primary payer. The information was either not reported or was illegible."

• Issue: Palmetto GBA will reject a claim when there was a mismatch between the MSP type submitted on an electronic claim and the specific patient's Medicare record
  • Palmetto GBA has implemented new MSP messaging to assist providers in quickly identifying claims that have rejected for incorrect MSP type based on information Medicare has on file. The new messaging is effective for claims processed on and after February 27, 2019. You will see CARC P6 and RARC N541 for these situations.
  • Claim Adjustment Reason Code P6, Reason and Remark Code N541: Mismatch between the submitted insurance type code and the information stored in our system
• Resolution
  • Review the Palmetto GBA article Valid MSP Types for Electronic Claims to assure the patient’s MSP type billed on your electronic clam is valid for the individual patient’s MSP type
  • Review the Palmetto GBA article Are Your Medicare Secondary Payer (MSP) Claims Rejecting? for proper placement of the MSP indicator on your claim
  • Make any necessary corrections to the patient’s MSP type and resubmit your claim
• Issue: When billing electronically, you must provide details regarding how the primary insurer handled the patient’s claim
• Resolution
  • The ASC v5010 format allows for electronic submission of primary payer information for MSP claims using the correct loops and segments
  • Review the Palmetto GBA article Electronic Submission of MSP Claims for proper claim submission of MSP payment information
  • Make any necessary corrections to the claim to provide the required information and resubmit the claim

Review the Palmetto GBA Medicare Secondary Payer (MSP) web page for additional MSP resources and the Washington Publishing Company website for Reason and Remark code descriptions.

Last Reviewed: 03/23/2026

Are you unsure if Medicare should pay as the primary or secondary insurer for your patient? Use our MSP tool to answer your questions and find your solutions. The questionnaire is easy and quick to use for all of your patients.

Before You Begin: Facts to Know

• For patients that have both Medicare and Medicaid and no other insurance, Medicare is the primary payer
• In most cases, federal law takes precedence over state laws and private contracts. Even if a state law or insurance policy states that they are a secondary payer to Medicare, the MSP regulations should be followed to determine the correct primary payer.
• Medicare records may not reflect the patient's current insurance status. If you find that there is a discrepancy between Medicare records and the patient's current insurance status, call the MSP Contractor at 855–798–2627 or TDD/TYY 855–797–2627. The MSP Contractor may also need to speak to the patient. However, providers are permitted to call.
• In some cases, if a patient or his/her spouse is working and is covered by an employer group health plan (EGHP), you must know the number of people employed by the company in order to use this tool most effectively. Either you or the patient may contact the employer to obtain this information.
• Providers are required to file claims on behalf of their Medicare patients, including patients for whom Medicare is the secondary payer
• These claims must be filed electronically, unless you qualify for a waiver to submit paper claims

Last Reviewed: 03/23/2026

If the primary payer for the service continues to recognize consultation codes, physicians and others billing for these services may either:

• Submit an evaluation and management (E/M) code that is appropriate for the service to the primary payer and then report the amount actually paid by the primary payer, along with the same E/M code, to Medicare for determination of whether a payment is due
• Submit a claim to the primary payer using a consultation code that is appropriate for the service and then report the amount actually paid by the primary payer, along with an E/M code that is appropriate for the service, to Medicare for determination of whether a payment is due

Last Reviewed: 03/23/2026