The party that pays the procedure must be clearly stated in the billing grid submitted to the IRB before the study started. You can look it up in TASCS or now OnCore depending on where it originated. If the procedure at the specific milestone is Ins in TASCS or OnCore, the procedure is billed to Insurance or the Patient themselves if they have no coverage. If it's an R, then it's research items and paid by the study via EFS. O was also used in TASCS to designate procedures performed by study staff that would be paid as labor to a Nurse, CRA, or PI.
There are some items, usually specifically called out in the invoiceables table for the study that are normally paid for by Insurance but should be paid for by the study, and usually invoiced by us to the sponsor in the event they occur outside of the normal Standard of Care schedule.