Associating Attachment Submissions to a Claim

All attachment submissions must be associated with a Professional (837p) claim or an Institutional (837i) claim. All payers have this requirement; however, each payer's process is different. In this section, we describe how specific payers associate attachment submissions with the correct medical claim.

The Attachment Control Number (ACN) is a key piece of information for all claims requiring attachments. It uniquely associates a claim with all attachments sent by providers and other submitters. It also works for Professional claims or Institutional claims. First, we'll use a Professional claim as an example.

As a medical payer, L.A. Care uses the EDI Loop 2300, using a couple of different EDI segments: the Claim Note (NTE) and the PWK (Paperwork) segment. These two segments apply to Professional claims (we'll describe Institutional claims usage in the next section).

For transactions with L.A. Care, submitters must use the claimNote object and its additionalInformation field to add the phrase "Claim Attachment Submitted." Consult the mapping guide and the 837p X12 standards documentation for more details on this segment:

claimNote (Object)Claim Notes/Claim InformationS



Description to clarify the related data
elements and their content.
1/80 R

For attachment purposes, L.A. Care requires the additionalInformation field. It's also a Required attribute from the 837p Implementation Guide.

In the claim, L.A. Care uses the Claim Supplemental Information (PWK) segment to describe each attachment for the current transaction. Each individual attachment document receives its own PWK segment, so a claim will have multiple instances of this segment when multiple attachments get submitted.

Here's the relevant part of the PWK segment as described in our Professional Claims JSON-to-EDI Mapping documentation:

claimSupplementalInformation (Object)S



Claim ID number for
clearing houses
1/50 R

  reportInformation (Object)



Code that describes the
attachment contents.
Ex: 08 = Plan of Treatment
2/2 R




Code that describes
how the attachment is sent.
Example: BM = By mail.
1/2 R




Identifies an electronic
attachment. The ACN
appears in the TRN02
field for an attachment.
2/80 S

NOTE: For your reference, the Attachment Submission 275 transaction contains the ACN. It is submitted in Loop 2000A, element TRN02, denoted as the field providerAttachmentControlNumber in the JSON request body.

The PWK segment uses the claimNumber field to contain the Claim ID for immediate reference. Following it is the reportInformation object. It defines the attachment information for the claim:

  • The attachmentReportTypeCode (required) uses a two-digit alphanumeric code to describe the title or essential category for the document, such as 'Treatment Diagnosis' (05). They are called Report Type codes, and can be found on Page 185 of the ASC X12 Consolidated 837p Guide;
  • The attachmentTransmissionCode (required). Defines how the attachment is submitted as part of the claim;
  • The attachmentControlNumber field appears in the PWK segment. It's the value associated with the specific attachment . This field only applies when the attachment is transmitted electronically.
NOTE: Each electronically submitted document in the claim will have its own Attachment Control Number.

Did this page help you?