For others, it's not a deadline.
There is a "hardship" exception for some that permits them not to sign up any kind of health insurance at all without facing a penalty - the hardship being problems they've encountered with Obamacare and its malfunctioning website HealthCare.gov.
There will also be a "good faith exception" for others, according to a senior Obama administration official.
"We'll have a special enrollment period," the official said last week, for "all those who make a good faith effort to get enrolled by the deadline" but fail to do so.
The official did not say how the government would determine whether or not the effort was made in good faith.
