"The Affordable Care Act affects each organization differently as the impact on many fronts will persist well beyond the 2014 period with many variables to consider," Portalatin said.

The employee benefits consulting firm surveyed about 900 employers nationwide to gauge their preparation for the changes taking place in 2014.

Some employers said they're trying to protect themselves against big jumps in enrollment by raising employee contributions for coverage. Thirty percent of respondents told Mercer they'll require workers to kick in more for dependent coverage, and 13 percent will raise the contribution level for employee coverage.

The majority of the employers (78 percent) also said they'concerned about the communication requirements associated with the new law — such as educating employees about their choices and supporting informed decision-making. Poll after poll has found the majority of Americans are confused, and largely unaware, of the changes presented by PPACA.

Tracy Watts, Mercer's health care reform leader, said the excise tax that goes into effect in 2018 might have the biggest impact on employer-sponsored coverage, despite the fact that no one's really talking about it. To avoid a 40 percent excise tax, employers must keep total health plan cost below a threshold of $10,200 for an individual and $27,500 for a family in 2018. To combat the tax, employers said they're focusing on high-deductible consumer-directed health plans (either by adding a plan or taking steps to increase enrollment in an existing plan), and expanding workforce health management programs.

While few large employers plan to terminate their medical plans and send employees to the public health exchanges (just 7 percent of those with 500 or more employees), many said they'd consider using a private health exchange.

Mercer not long ago launched its private exchange, which drew dozens of carriers. Open enrollment will begin this fall with the first policies going into effect Jan. 1.