The Obama administration has targeted enrolling at least 2.7 million young adults through the state and federal exchanges for coverage in 2014. But there's still a big question about whether young adults will enroll, or just opt to pay the penalty, which for the first year could be as little as $95.

"It's that age bracket that feels like they don't really need coverage, so they can get away with not paying that cost right now," said Kristie Arslan, president & CEO of the National Association of Self-Employed (NASE).

Arslan says her members will be buying their insurance on the exchanges for next year. She recently attended a White House briefing on ACA enrollment plans. She's worried, despite assurances from Washington, that too many young invincibles opt out of enrollment.

"If they don't get the ratio that they need in the state-based exchanges, it's going to be like high-risk pools," she said. "They're going to be very unaffordable, because you'll have all sick people and no healthy people."