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Provider Notice Issued 06/16/2021

Date:    June 16, 2021


To:       All Medical Assistance Program Providers


Re:      Medicare Beneficiary Identifier (MBI) Field Completion for 837P Crossover Claims



This notice informs providers of a new claim completion requirement related to the Medicare Beneficiary Identifier (MBI) on Medicare crossover 837P claims. This requirement applies to fee-for-service claims for patients enrolled under both Original Medicare and Medicare Advantage Plans. The new billing requirement only impacts 837P claims submitted through a clearinghouse, not those submitted through the MEDI system.


An HFS change in mapping of the MBI was necessary to allow tertiary claims to adjudicate correctly. Due to the mapping change, 837P crossover claims that are submitted through a clearinghouse must identify claim filing indicator code “MB” (for Medicare B) in Loop 2320, Segment SBR09. The actual MBI continues to be entered in Loop 2330A, Segment  NM109.


Providers must inform their vendors of this mapping change. Claims that do not contain the claim filing indicator code “MB” will be rejected with error code K22 – MBI Does Not Match # on File.


Special Note for Providers of Encounter Clinic Services Who Bill Medicare Primary on the Institutional Claim Format:

Providers who are required to bill Medicare as the primary payer on the institutional claim format  must change the claim filing indicator “MA” to “MB” in Loop 2320, Segment SBR09 of the 837P before billing Medicaid as the secondary payer.


Questions regarding this notice may be directed to a billing consultant in the Bureau of Professional and Ancillary Services at 877-782-5565.



Kelly Cunningham, Administrator

Division of Medical Programs​


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Illinois Department of Healthcare and Family Services

JB Pritzker, Governor • Theresa Eagleson, Director