"As used in connection with the Affordable Care Act: A group health plan that was created—or an individual health insurance policy that was purchased—on or before March 23, 2010. Grandfathered plans are exempted from many changes required under the Affordable Care Act. Plans or policies may lose their “grandfathered” status if they make certain significant changes that reduce benefits or increase costs to consumers. A health plan must disclose in its plan materials whether it considers itself to be a grandfathered plan and must also advise consumers how to contact the U.S. Department of Labor or the U.S. Department of Health and Human Services with questions. (Note: If you are in a group health plan, the date you joined may not reflect the date the plan was created. New employees and new family members may be added to grandfathered group plans after March 23, 2010).
What grandfathered plans do and don't have to cover
Here's a quick look at the consumer protections that do and don't apply to grandfathered plans:
All health plans must:
End lifetime limits on coverage
End arbitrary cancellations of health coverage
Cover adult children up to age 26
Provide a Summary of Benefits and Coverage (SBC), a short, easy-to-understand summary of what a plan covers and costs
Hold insurance companies accountable to spend your premiums on health care, not administrative costs and bonuses
Grandfathered plans DON'T have to:
Cover preventive care for free
Guarantee your right to appeal
Protect your choice of doctors and access to emergency care
Be held accountable through Rate Review for excessive premium increases
In addition to the above, grandfathered individual health insurance plans (the kind you buy yourself, not the kind you get from an employer) don't have to:
End yearly limits on coverage
Cover you if you have a pre-existing health condition"
https://www.healthcare.gov/what-if-i-have-a-grandfathered-health-plan/