Flexibility Through Lower Expenses Health Care Act or the FLEX Act This bill provides statutory authority for certain short-term, limited-duration health insurance plans and association health plans. The bill permits short-term, limited-duration plans to provide coverage for a period of less than 12 months, not including extensions. Under current law, such plans are exempt from certain market requirements of the Patient Protection and Affordable Care Act, such as coverage of individuals with preexisting conditions. The bill further permits groups or associations of employers to sponsor fully insured group health plans as if they were employers. Such plans may not discriminate based on the health factors of any prospective plan participant for the purpose of granting an employer's membership in the association or determining a participant's eligibility for benefits or premium amounts.