Identify the claim to reverse using the original Prescription/Service Reference Number (Field ID 402) and Authorization Number (Field ID 503) returned in the original B1 approval response
Construct a D.0 B2 (Claim Reversal) transaction: Header segment with transaction code B2, same BIN/PCN/Group as original claim; populate Claim segment with original prescription reference number and date of service
Include the original Authorization Number in Field ID 503 of the reversal request; this is required by most PBMs to match the reversal to the specific paid claim
Transmit over the same switch used for the original claim; receive B2 response with transaction response code C (Reversal) indicating success, or rejection code if the claim is outside the reversal window
Record the reversal response and update the dispensing system to mark the claim as reversed; trigger any downstream financial adjustments (co-pay refund to patient if applicable)
If the reversal is rejected because the claim is outside the PBM's allowed reversal window, initiate a manual claim adjustment request with the PBM or plan sponsor
Known gotchas
Most PBMs enforce a claim reversal window (commonly 30–90 days from date of service); claims older than this window cannot be reversed electronically and require a manual reconciliation process with the PBM
A B2 reversal does not automatically trigger a refund of co-pay collected from the patient; the pharmacy must manage the patient refund separately from the PBM financial reversal
If the original claim was submitted across multiple transactions (e.g., compound claim with multiple ingredient lines), each line may need a separate reversal; confirm PBM-specific reversal rules for compound claims in their companion guide
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