Short answer: A Minimum Essential Coverage plan provides the baseline preventive coverage that satisfies the ACA’s coverage definition. Larger employers sometimes use thin MEC plans to manage employer-mandate penalties.
“Minimum essential coverage” (MEC) is the ACA’s baseline standard for what counts as having health coverage. A standalone MEC plan typically covers ACA preventive services and little else, and applicable large employers sometimes offer one to avoid the larger ‘A’ employer-mandate penalty. MEC is a low bar; comprehensive ACA small-group plans already far exceed it, so MEC-only plans are usually paired with other coverage rather than used as a worker’s main plan. (Note: MEC differs from ‘minimum value,’ which measures whether a plan is robust enough.)