Next Steps for MSP Denials

If you've received a denial on a Medicare claim due to Medicare being billed as the primary payer when it should have been secondary, you might be wondering what to do next. The instinct may be to file an appeal—but that's not always the right step.

When Medicare is incorrectly billed as primary, the denial is typically due to a coordination of benefits (COB) issue. In these cases, you should submit an MSP Inquiry Form, not an appeal.

This form allows the Medicare Administrative Contractor (MAC) to investigate and correct the COB information. Once the COB is updated, you can resubmit the claim correctly.

When submitting the MSP Inquiry Form, be sure to include documentation from the primary insurance that confirms Medicare should be secondary. This helps the MAC verify the correct payer order and process the correction more efficiently.

Key Steps for Suppliers

  • Submit an MSP Inquiry Form if Medicare was billed as primary but should have been secondary.
  • Include COB documentation from the primary insurer with the form.
  • Contact the MAC to correct COB records before initiating any appeals.
  • Only appeal if the claim was correctly submitted and still denied for other reasons.

CMS and Noridian have published guidance confirming this process. For example:

  • CMS MLN Matters SE21002 advises providers to review billing orders and contact the MAC before appealing.
  • Noridian's MSP resources clarify that MSP denials are too complex for reopening and often require COB updates instead.

By following the correct process, suppliers can avoid unnecessary delays and ensure claims are handled efficiently. If you need help locating the MSP Inquiry Form or understanding the COB correction process, reach out to your MAC's supplier contact center.

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