Identifying prospects who purchased their plan during the 2016 SEP timeframe isn't difficult, but doing the same with prospects who made some kind of change to their 2016 plan won't be as cut and dry.
Real life example: Spouse is aging into Medicare in the middle of the year. If the spouse primary is under 65 and stays on the plan with Blue Cross we are still getting commission with the change. If primary was the spouse who is going into Medicare, remaining spouse has a new policy, and we are not paid, either on or off-exchange. I had a few clients aging into Medicare this year, after the change I checked my commission statements, and every time I was paid according to this rule.