A smaller but still substantial number of respondents expected active employees and spouses now on company plans to seek exchange coverage next year. Companies contemplating such a move often plan to give employees money now spent on the corporate plan to buy into the marketplaces, analysts say.
Darling downplayed the idea that less generous employer benefits are behind the potential move to exchanges.
"They are not reducing their benefits," she said at a Wednesday news conference. "The dollars that they are putting into health care are going to go up next year."
Full-time employees seeking exchange coverage in 2014 are likely to be lower-paid workers in retail and hospitality who don't take the company plan because they can't afford it, she said. The ACA marketplaces come with substantial government subsidies for those with family incomes of up to about $94,000.
Fifteen percent of the employers in the NBGH survey saw spouses or other dependents shifting to the online marketplaces next year; 12 percent saw full-time workers making the switch.
Last week Kaiser Health News reported that United Parcel Service would drop about 15,000 working, white-collar spouses from its company plan next year but would continue to cover nonworking spouses.
While large employers are barred from buying on state exchanges at least until 2017, their workers and dependents could buy plans as individuals.
Big corporations are also looking closely at private health insurance exchanges for employees and retirees. Like the public ACA exchanges, private exchanges offer an online menu of comparable policies for consumers to choose from.
Private exchanges are offered only to a limited set of potential members, however -- say, employees and retirees at select companies. They also lack the public exchanges' government subsidies.
About a third of the companies in the NBGH poll are considering moving employees into private exchanges, promoted for their potential to control costs by fostering more choices in the employer-sponsored insurance market.
"At this point it's still mostly interest," Darling said. "There's a lot of talk."
She expects quicker adoption, however, of private exchanges for retirees.
Wed, Aug 28 2013