CMS Pub. 100-04, ch. 28, § 80.3.2

A. Outbound Coordination of Benefits (COB)

The outbound COB transaction is a post-adjudicative transaction. This transaction

includes incoming claim data as well as COB data. A/B MACs (B)/DME MACs are

required to receive all possible data on the incoming ASC X12 837 although they do not

have to process non-Medicare data. However, they must store that data in a store-and-forward repository (SFR). This repository will be designed by the shared system. This

data must be re-associated with Medicare claim and payment data in order to create an

outbound ASC X12 837 COB transaction. The shared systems maintainer is to use post-adjudicated Medicare data (data used from history and reference files to adjudicate the

claim) instead of data received when building the outbound COB transaction. A/B

MACs (B)/DME MACs must retain the data in the SFR for a minimum of six months.

The ASC X12-based flat file is the format to be used to re-associate all data required to

map to the outbound ASC X12 837. The translator will build the outbound ASC X12 837

COB from the ASC X12-based flat file.

The shared system maintainer must create the outbound ASC X12 837.

B. Summary of Process

The following summarizes all the steps from receipt of the incoming claim to creation of

the outbound COB:

● A/B MAC (B)/DME MAC’s translator performs syntax edits and maps

incoming claim data to the ASC X12 flat file;

● Standard system creates implementation guide and Medicare edits for the flat

file data;

● Medicare data on ASC X12 flat file is mapped to the core system;

NOTE: No changes are being made to core system data fields or field sizes.

● Non-Medicare data (and Medicare data elements where field sizes are in

excess of the core system) are written to the store-and-forward repository; and

● Adjudicated data is combined with repository data to create the outbound

COB.