What does it mean when an employer-sponsored health plan is described as 'minimum essential coverage' versus 'minimum value' coverage?

These are two distinct legal standards under the ACA with different consequences for employees. Minimum essential coverage (MEC) means the plan qualifies as health insurance coverage, which historically avoided the individual mandate penalty. Minimum value (MV) means the plan pays for at least 60% of total covered benefit costs — roughly equivalent to a Bronze-level ACA plan. An employer can offer coverage that satisfies MEC but not MV (for example, a plan with an extremely high deductible that covers almost nothing). If an employer's plan does not meet minimum value, employees may be eligible for ACA marketplace subsidies even if they have an offer of employer coverage.