According to the Affordable Care Act, a plan must exist prior to which date to be considered grandfathered?

To be designated as a grandfathered health plan under the Affordable Care Act (ACA), a health insurance plan must have been in existence on or before March 23, 2010. This date is significant because it marks the enactment of the ACA itself. Plans that were already in force before this date are allowed to retain their grandfathered status, meaning they can avoid some of the ACA's requirements while still providing coverage.

The purpose of this provision was to ensure that people who had existing insurance plans could keep them without facing the costs or requirements imposed by the ACA that might not have been in place prior to its enactment. Such plans are not subject to certain mandates of the ACA, such as the requirement to provide specific essential health benefits, although they still must comply with many other regulations.

Choosing any date after March 23, 2010, would mean that those plans would not be grandfathered and would therefore have to comply with the full set of ACA demands, which reflects why the correct answer is March 23, 2010.