"It was the carrot, not the stick," Eyles said, of what motivated people to enroll, noting that the Obama administration and Affordable Care Act advocates emphasized the new plans' benefits and not the penalties in their massive outreach efforts.
Eyles added, the mandate's financial hit to people who don't comply is "weak," and typically will cost less than the new insurance premiums they would have to pay to comply.
Under Obamacare, most people must have some kind of health-care coverage—through their employer, the individual insurance market, Medicare or Medicaid—by March 31 of this year or pay a tax penalty next year. That penalty is equal to $95 or 1 percent of a person's taxable income, whichever is higher.
To help people comply with the mandate, the ACA established government-run health exchanges to sell private insurance to individuals and families. Those exchanges saw a flood of more than 3 million people in just the last month of open enrollment, bringing total sign-ups to more than 7 million.
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Christina LaMontagne, a health cost analyst for the price-comparison site NerdWallet, said that penalty "wasn't really that significant" in getting people to enroll, from what her company heard in interviews it did with people exploring their insurance options.
Instead, LaMontagne said, "We heard people saying they really valued health insurance ... we heard again, and again and again that people wanted health insurance, and they were sick of finding these short-term solutions."
"People have expressed a desire to be insured and have over time pieced together temporary solutions as their employment or health situations have changed," she said. "One common thread were heard from parents is that often some family members were insured while others were not. ... For these families, [the Affordable Care Act] offered an opportunity to get everyone covered in some way and to fill in gaps across the family unit."
And many of those people qualified for government subsidies to help them offset the cost of the insurance plans. Those subsidies are available to people who earn less than 400 percent of the federal poverty limit—about $46,000 for a single person and about $94,000 for a family of four.
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"Those subsidies just changed the game," LaMontagne said, crediting them with being a significant motivating factor for enrollees. About 80 percent of enrollees on the exchanges qualified for the subsidies.
Another skeptic of the power of the mandate, Bankrate.com analyst Doug Whiteman, who noted that his company's surveys of the uninsured "found a very surprising lack of knowledge" about the ACA "just a couple of weeks" before the sign-up deadline. Only 48 percent, for example, could correctly identify the deadline, Whiteman said.