all individuals not covered by an employer sponsored health plan

A shared responsibility requirement, commonly called an individual mandate,^[17][18] requires that all individuals not covered by an employer sponsored health plan, Medicaid, Medicare or other public insurance programs, purchase and comply with an approved private insurance policy or pay a penalty, unless the applicable individual is a member of a recognized religious sect exempted by the Internal Revenue Service, or waived in cases of financial hardship.^[19]

http://en.wikipedia.org/wiki/Patient_Protection_and_Affordable_Care_Act