Section 890.1308 - Carrier participation(a) All carriers who participate in the FEHB Program and provide benefits to enrollees in the geographic areas selected as demonstration project areas must participate in the demonstration project, except as provided for in paragraphs (b), (c), and (d) of this section.(b) Carriers who have less than 300 FEHB enrollees may, but are not required to, participate in the demonstration project.(c) Carriers may, but are not required to, participate in the demonstration project if their service area overlaps a small portion (as determined by OPM) of a demonstration project geographic area.(d) Carriers offering fee-for-service plans with enrollment limited to specific groups will not participate in the demonstration project.