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MSP Frequently Asked Questions

Updated: 04/08/2014

Question: Why are my MSP Claims Denied?

Denial reasons include, but are not limited to, the following:

  • Electronic claims:
    • Submitted with incorrect MSP type.
    • Submitted with incorrect CARC codes.
    • Tip: use the CGS MSP Job Aid to ensure you are submitting the required information correctly. The job aid includes MSP types and other helpful tips.
  • Paper claims:
    • The primary insurer's explanation of benefits (EOB) is illegible.
    • The primary insurer has denied all or part of the claim, but the reasons for the denials are not included. This occurs often when an EOB is submitted without the denial code remarks page. Before Medicare can consider payment, an explanation of the denial is necessary to determine if the services can be allowed by Medicare.
    • The date of service and/or name on the primary insurer's EOB does not match the date of service and/or name on the claim submitted to Medicare. Medicare does not accept any handwritten information on the EOB to process as secondary.
    • The EOB from the primary insurer is missing information or has been "cut off". If the header information is missing, CGS cannot determine which column is primary allowed and which one is paid.
    • Billed amount on claim does not match billed amount on EOB. Services submitted to Medicare must match services submitted to primary insurance. (e.g., procedure code, billed amount).
    • Claim submitted for co-pay or coinsurance only. Billed amount must be same as amount billed to primary insurance.
  • All claims:
    • Primary insurance has been cancelled or terminated. The cancellation or termination date must be included.
    • The explanation of benefits is from the patient's supplemental insurance. Supplemental plans pay secondary to Medicare.


  • If your initial claim denied for any reason above, make the necessary corrections and submit as a new claim.
  • Do not submit copies of the Medicare EOBs. The only EOB required is from an insurer that pays primary to Medicare.

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Question: What information is needed when submitting an overpayment voluntary refund that has Medicare Secondary Payer (MSP) involvement?
  1. Use the Overpayment Refund Form to ensure you are sending all required information. Access the form and instructions for completing it from the CGS website.
  2. When sending a refund with MSP involvement, attach a copy of the primary insurer's Explanation of Benefits (EOB).
  3. Complete the physician/refund portions and use the reason codes listed on the bottom of the Overpayment Refund Form to identify the reason for your refund.
  4. The date of service (DOS), beneficiary's Health Insurance Claim (HIC) number, and the reason you are submitting a refund are required.
  5. When refunding for multiple beneficiaries, include sufficient documentation to show how much money is being refunded for each claim.
  6. We recommend that you refund no more than 20 beneficiaries per check.
  7. We recommend that you not combine overpayment voluntary refunds with MSP involvement and overpayment voluntary refunds for NMSP in the same request.
  8. We recommend that you not combine overpayment voluntary refunds with "demand" check refunds (these are overpayments identified by CGS).

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Question: What is OTAF?

When a provider signs a contract with a primary insurer to accept their payment amount as "payment in full" for covered services, the provider is "obligated to Accept Financial" no more than the allowable from any other source.

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Question: I file my claims electronically, but they still get denied for MSP type. Why?

MSP claims will be denied if the MSP type entered on the claim is not correct. Example the claim is submitted with type 12 for working aged and the beneficiary is really disabled. The claim should have been submitted with MSP type 43. Please see our net course entitled Medicare Secondary Payer billing MSP claims electronically for instructions on billing with MSP types.

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Question: Do I have to take the Primary Insurer's allowed amount in full when I am not contracted with the primary insurer?

No, if you are not obligated to accept or voluntarily accept, then you are not obligated to take the primary insurer's allowed amount.

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Question: Does Medicare cover co-pays on secondary claims?

Medicare does consider coverage on co-pays following our normal claim processing guidelines.

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Question: I sent in a voluntary refund check for MSP; however, I still get an overpayment letter. Why?

The most common issue that creates overpayment when a check is provided is when a valid EOB is not included with the Check. Please make sure you have a valid legible EOB submitted with each Refund request, along with the HICN, DOS and reason for refund.

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Question: I sent in my check for MSP overpayment, but it does not get processed with the Explanation of Benefits information. Why?

Often providers send large refunds that include MSP reasons with non MSP reasons. If a check is sent in with both and no EOB is attached to indicate MSP it will be processed as Non MSP. In order to reduce this and expedite the refund process it is suggested that you send all MSP related claims on one check and all non MSP related claims on a separate check. In addition, when sending multiple beneficiaries on the check; include EOBS for each beneficiary and how much is being refunded for each.

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