If someone has COBRA available but they opt out in order to purchase a health plan through the marketplace, can they qualify for a subsidy? My FMO says yes, but I'm not so certain.
Yes. If they are ELIGIBLE FOR it but have not ENROLLED IN it.
If they actually enroll in COBRA, then they are stuck until COBRA is over or until it is OEP or unless there's another reason they get an SEP.
(Actually, to be strictly technical, they could disenroll in COBRA and they could be eligible for subsidies in the month in which they are not enrolled in COBRA. But they can't get an SEP by voluntarily disenrolling.)