Implement loop 2320 coordination of benefits in an X12 837 claim to pass primary payer adjudication data when billing a secondary payer

Verified steps

1. In the 2300 claim loop, confirm the SBR09 claim filing indicator code reflects secondary coverage and populate MOA segments if Medicare is the secondary payer to carry remittance advice remark codes from the primary adjudication
2. Build the 2320 other subscriber information loop with SBR identifying the primary payer relationship, OI to indicate patient signature and assignment, and AMT segments to carry the primary payer paid amount using qualifier D
3. Populate the 2330A other subscriber name loop and 2330B other payer name loop with NM1 segments identifying the primary insured and the primary payer respectively, including the primary payer's payer ID in REF
4. In the 2320 loop, add CAS segments to carry each claim-level adjustment from the primary payer ERA, using the appropriate adjustment group code such as CO for contractual obligations and the specific CARC code and adjustment amount
5. At the service line level, create 2430 line adjudication information loops under each SVD segment to carry line-level primary payer paid amounts and CAS line adjustments for each procedure code
6. Ensure the sum of primary paid amount plus all CAS adjustment amounts in 2320 equals the total billed amount on the original claim; secondary payer systems use this arithmetic to calculate the remaining patient or secondary liability