Eligibility and benefits related to prescription drugs require additional information not spelled out in the guide:
RxBin - this is a field that indicates "who" the claim is to be sent to.
RxPCN - this is a field that indicates "who is the plan" - Of course, this could be processor dependent - a standard RxPCN or unique .....it's up to each plan/processor to determine this field.
This is usually printed on the member's ID card. Please validate the appropriate usage for a standard reporting of this information in the 270 to the PBM:
RxBIN - report in the 2100A Information Source loop as the NM109 Payer Identifier, with an NM101 qualifier of PR (meaning Payer), and an NM108 qualifier of PI (meaning Payor Identification). Alternatively, should we use the NM108 qualifier 46 (meaning Electronic Transmitter Identification Number (ETIN))?
RxPCN - report in the 2100C Subscriber loop as the REF02 with an REF01 qualifier of N6 (meaning Plan Network Identification Number)
The 005010X279A1 Technical Report Type 3 (TR3) does not explicitly address your question.
As you note, the Information Source is reported in loop 2100A segment NM1 Information Source Name. Neither of the NM108 Identification Code Qualifiers 46 or PI is constrained to a specific code list, so using either with the RxBIN would comply with the TR3. Please note that the Information Source in the 270/271 transaction may not always be the same entity to which the 837 will be sent.
Similarly, the loop 2100C segment REF Subscriber Additional Identification can be used to provide criteria for additional alternate search options as explained in section 1.4.8.5. The REF01 Reference Identification Qualifier N6 is not constrained to a specific code list, so using it with RxPCN would comply with the TR3. Similarly, using 18 (Plan Number) with RxPCN would also comply with the TR3.
For consistency, sending RxBIN in 2100A/NM109 using qualifiers NM101=PR and NM108=PI and sending RxPCN in 2100C/REF02 using REF01=N6 is recommended. Advance agreement with your trading partner is recommended appropriate.