Large and small employers are bracing for the sharpest increase in health care costs in more than two decades. The cost per worker is projected to go up an average of 11 percent next year, with employers' final costs expected to rise about 8 percent after making changes to health plans, the steepest since 2003, according to Marsh. More than a third of the 1,800 employers surveyed said they anticipated costs would rise at least 10 percent after making cuts. "This year was a rough year, and next year looks like it will be even rougher," said Beth Umland, director of employer research for health and benefits at Marsh.

From 2018 to 2027, health care costs could increase 76 percent, roughly twice the rate of general inflation, according to a survey by the Business Group on Health. Aon estimated employers' costs would rise 9.5 percent next year, pushing the average cost per employee above $19,000. Mike Pasterick, an executive at Aon, said this is impacting companies in a very material way.

About 160 million people under 65 who rely on employers for health insurance will confront higher costs and shoulder more of the burden. Workers are paying an average of 10 percent more in out-of-pocket costs in 2026, some $2,167 more than last year, Aon estimated. These kinds of increases are not sustainable, said Rosa Novo, benefits administrator for Miami-Dade County Public Schools.