A Revenue Integrity Series I Paper No.1 For ACA marketplace health plans, the period between May and August is what we call the Blackout Period: the interval between the close of open enrollment and the beginning of the next plan year's data submission cycle. Most plans treat this time as an administrative lull. The most sophisticated ones treat it as their single most valuable operational window. Here is our insider tip: what you do - or don't do - between May and August