X12 External Code Lists

The following are the external code lists established, maintained, and published by X12. The code maintenance group (CMG) identified after each list name below is responsible for maintaining the external code list. An asterisk (*) indicates maintenance responsibility is currently in transition from another industry group to the X12 CMG operating under the External Code List (ECL) subcommittee.

  • For a description related to a specific code list, hover over the code list name below.
  • For more detailed information related to a specific code list, click on the code list name below.
  • Training and Information material related to X12's External Code Lists and the External Code List Oversight Subcommittee are available here.
  • For help navigating on this External Code List page, or the detailed pages that follow, click here for online help.
139 Claim Adjustment Reason Codes (CMG03*)
507 Health Care Claim Status Category Codes (CMG03*)
508 Health Care Claim Status Codes (CMG03*)
886 Health Care Service Review Decision Reason Codes (CMG04*)
895 Insurance Business Process Application Error Codes (CMG02*)
958 Service Type Codes (CMG04*)
967 Provider Adjustment Reason Codes (CMG01)
973 Insurance Industry Specific Remark Codes (CMG01)
974 Claim Adjustment Group Codes (CMG01)
977 Error Reason Codes (CMG01)
979 Insurance Descriptor Codes (CMG01)
981 Service Type Descriptor Codes (CMG01)