Implement an NCPDP D.0 coordination of benefits (COB) claim to bill a secondary payer after primary adjudication

Verified steps

1. After receiving a primary payer B1 approval, capture the primary payer response data required for COB: Authorization Number (Field ID 503), Ingredient Cost Paid (Field ID 506), Dispensing Fee Paid (Field ID 507), Tax Exempt Indicator, and Patient Pay Amount (Field ID 505)
2. Construct the secondary payer B1 COB claim: in the Other Payer Amount Paid fields (Group ID AM, Field ID 431), include the amount paid by the primary payer and the primary payer's Authorization Number; set OtherPayerCoverageType and OtherPayerAmountPaid appropriately
3. Route the COB claim using the secondary payer's BIN/PCN/Group ID; the secondary payer adjudicates based on the patient's remaining liability after primary payment
4. Receive the secondary payer response: parse secondary Patient Pay Amount; the patient's final out-of-pocket cost is the secondary Patient Pay Amount (which should reflect remaining liability after primary payment)
5. If a third payer exists (e.g., manufacturer copay card as tertiary), construct a third COB transaction referencing both prior payer paid amounts; submit to the copay card BIN/PCN
6. Retain all adjudication response records from each payer layer; reconcile final patient out-of-pocket against amounts collected at the point of sale