Vendor
Medicare (CMS)
Payers. MACs each publish companion guides. ISA qualifiers vary by MAC (e.g. ZZ for most).
https://www.cms.govSupported transactions
Per-transaction requirements
Transaction 837I
Details →ISA05/07 = ZZ/ZZ · GS01 = HC · GS08 = 005010X223A2
2 required · 1 fixed value