3. What is the Coverage Gap Stage? Posted on September 11, 2017 at 12:14 pm.Written by advantage_admin When a member reaches this limit, he/she goes into a gap stage, which means that from that particular moment their coverage will be limited, including discounts for certain prescriptions, and everything else will have to be covered out of pocket. Post navigation 3. Which plans cover Medicare Part D?1. What is Triple-S Advantage?