Final answer:
The employer mandate under the Affordable Care Act requires all employers with more than 50 full-time employees to offer health insurance, which often includes contributory employer-sponsored group health insurance plans.
Step-by-step explanation:
The minimum number of employees that must be insured under contributory employer-sponsored group health insurance plans is affected by the employer mandate, which is part of the Patient Protection and Affordable Care Act (ACA). Under this mandate, all employers with more than 50 full-time employees are required to offer health insurance. While this doesn't specify a minimum number for contributory plans specifically, the implication is that businesses with over 50 employees must offer some form of health insurance, and this can typically include participatory contributions from employees.
Many lower-paying jobs do not include health insurance as a benefit, and despite government programs, a significant number of Americans remain uninsured. The introduction of the Affordable Care Act attempted to mitigate this by offering health insurance through employer groups and government-sponsored exchange markets, by mandating insurance purchase, and by preventing denial based on preexisting conditions.