The IRS will be somewhat hamstrung with what the Service can and can't do to you for failing to buy insurance under the Affordable Care Act (the "ACA"). Read my article about the IRS' enforcement limitations in the ACA.
Essentially, if the IRS can't jail you for failing to pay for insurance, sue you, levy your bank or wages, take your property or charge you interest on penalties, then enforcement on ACA penalties is limited to taking your refunds from year to year. Crafty taxpayers will avoid refund scenarios by opting for less withholding or refusing to make required quarterly estimate payments. What happens if taxpayers don't withhold enough or pay quarterlies? They incur more penalties. The IRS can collect those penalties only by taking a taxpayer's re...er, wait. See the problem?