(Todd Warnock)
NorthBay Adventure is the kind of small business that could be expected to buy medical insurance for workers under sweeping health-act rules taking effect in 2014. But executive director George Comfort says that's not likely to happen.

Instead, NorthBay became self-insured last year, paying most of its workers' health costs directly, a practice more typical of large employers. The decision to self-insure was about free choice, savings and what's best for his company, Comfort says.

But others see it as a threat to the Affordable Care Act. As more small employers like NorthBay avoid the health act's requirements through self-coverage, small-business marketplaces intended to cover millions of Americans could break down and become unaffordable, they say.

"What you've got is basically a loophole for the small employer to get out of the ACA requirements,' says Robert Laszewski, a Virginia-based consultant and former insurance executive.

To employees, medical self-insurance looks like a regular health plan. Self-insured employers pay for most worker health costs directly, though they contract with an insurer or other company to administer claims. The employers also buy coverage known as stop-loss for claims exceeding a certain amount. Brokers say a growing number of firms see such plans as low-cost alternatives to conventional coverage because they're exempt from ACA requirements such as insurance taxes and specified benefits.

NorthBay, which is located on the north shore of Maryland's Chesapeake Bay and delivers outdoors education to sixth-graders, saves some 45 percent on self-insured health costs for its 60 or so covered employees compared with the price of regular coverage, says Comfort.