Short answer: Eligibility usually depends on full-time status (commonly 30+ hours a week), being a W-2 common-law employee (not a 1099 contractor), completing any waiting period, and, for owners; the business’s entity type and the carrier’s owner rules.
Most group plans tie eligibility to full-time status, generally 30 or more hours per week, and to being a common-law W-2 employee; 1099 contractors are typically excluded. New hires must also finish any waiting period (up to 90 days). Owners’ eligibility depends on the business structure (sole prop, partnership, S-corp, etc.) and the carrier’s specific owner-eligibility rules. Part-time and seasonal status, and state rules, can also affect who qualifies.