CMS Pub. 100-04, ch. 27, § 10

System

(Rev. 4009, Issued: 03-23-18, Effective: 04-23-18, Implementation: 04-23-18)

The Common Working File (CWF) is the Medicare Part A and Part B beneficiary

benefits coordination and pre-payment claims validation system which uses localized

databases maintained by designated contractors called ‘CWF Hosts’. The CWF System

software is duplicated and utilized by the nine CWF Hosts localized databases to process

claims.

Each Medicare beneficiary is assigned to only one Host site based on beneficiary

geographic location. CWF Hosts maintain total beneficiary claim history and entitlement

information for the beneficiaries in their jurisdiction.

Each jurisdiction is a network of A/B Medicare Administrative Contractors

(MACs) and Durable Medical Equipment Medicare Administrative Contractors

(DME MACs), termed “Satellites,” and located in a defined geographic area

(sector). Each MAC within the sector is linked to its Host via

telecommunications through their respective CMS Virtual Data Center (VDC).

The Medicare Part A, B or DME processing system creates a nightly CWF file out of the

MACs processing region, containing claims data. The corresponding MAC’s VDC

transmits these files to the CWF Host. The CWF Host uses the CWF software and

determines the beneficiary's eligibility and entitlement status and uses that information to

decide what action should be taken on the claim. The CWF software also checks

incoming claims against all other claims types, referred to as A/B crossover, previously

processed and stored in claims history to prevent duplicate payments. The Host returns a

response file back to the VDC and the file is loaded to the MACs processing region. The

file will contain various disposition codes, trailers, and error codes, used by the

processing systems in automatic processing during the batch cycle. The responses are

applied to the pending claim allowing appropriate system action.