Group health insurance remains the most common form of coverage in the U.S., covering roughly 165 million people as of 2024. Employers typically pick up about three-quarters of the cost — with family premiums averaging nearly $27,000 in 2025 and workers contributing around $6,850 from their paychecks. But the rules governing how group plans work have changed significantly since the ACA was enacted.
A healthinsurance.org article by Louise Norris walks through the key reforms the ACA brought to both small-group and large-group markets. In the small-group market, premiums can no longer be based on a group’s medical history or industry — they can only vary by age, family size, location, and tobacco use. Plans must cover the ACA’s essential health benefits, out-of-pocket costs are capped, and young adults can stay on a parent’s plan until age 26. For large employers, the ACA requires those with 50 or more full-time workers to offer affordable, minimum-value coverage or face tax penalties. The article also covers what happens if you lose your job — noting that the ACA has made COBRA less of a necessity by opening up guaranteed-issue individual coverage regardless of pre-existing conditions.