Current PLB03-2 provides an identifier. This is most commonly the payers claim/ICN number. In the case of Medicare the HIC number is also provided. HIC is most often the Social Security Number. Non-Medicare payers report any internally assigned reference identifier for the related adjustment.
As a provider it would benefit to receive the patient's unique account number that is sent to the payer in the 837 transaction, CLM01. This is not needed in all PLB03-1 adjustment reason codes but certainly with many, example: FB-Forward Balancing and WO-Withholding.
Create a new reference identification value to allow the CLM01 to be returned in the PLB segment.