Beginning Jan. 1, new policies issued must cover a minimum share of health care expenses and offer 10 “essential health benefits”:

If a policy was in effect when the law passed in March 2010 and has not been changed significantly, people already on the plan could remain on it, and the plan would not have to meet the new requirements.

... but many people will need to purchase a new plan because:

• Many plans do not currently meet the law’s standards for coverage.

• Most people in the individual market do not keep their policies for more than a year, so most would not be eligible to be grandfathered.

• Insurance companies cannot change grandfathered plans or sell them to new customers, so they have incentive to cancel the policies.