Millions of people may be exempt from the requirement known as the individual mandate under rules issued by the Obama administration. Homeless people or homeowners who've been foreclosed upon can apply for an exemption. So can those whose utilities have been shut off, who have suffered domestic violence or who have experienced a death in their families.

In December, the administration said people whose existing health plans had been canceled wouldn't have to comply with the mandate. Last week, the government said that exemption will be extended through 2016. In a catch-all category, anybody who believes they've had a "hardship in obtaining insurance" can apply for an exemption — documentation is optional.

"If you're a consumer and you're looking at this, it leaves a lot of ambiguity," Dan Mendelson, the president of Avalere Health, a Washington consulting firm, said by telephone. "You don't know if you qualify for a hardship exemption but you are very likely to fall into one of these categories — or are able to get into one of these categories."