Many employers are betting that the Affordable Care Act’s requirement that all Americans have health insurance starting in 2014 will bring more people into their plans who have previously opted out. That, along with other rising expenses, is prompting companies to raise workers’ premium contributions, steer them toward high-deductible plans and charge them more to cover family members…

Some are dealing with rising expenses by making employees pick up a bigger share of the premiums for coverage of family members. Employees this year are responsible for an average 18% of the cost of individual coverage, but 29% of the cost of family coverage, according to a survey of employee health plans by the Kaiser Family Foundation and the Health Research & Educational Trust…

Starting in 2015, companies employing 50 or more people must offer affordable health-care coverage to anyone working 30 hours a week or more…

But affordability is measured using the cost of individual coverage, capping the cost at 9.5% of income, Ms. Ho said.