INDIANAPOLIS – Big companies think health care legislation will increase their costs, but most expect to continue offering subsidized benefits to workers, according to a Towers Watson study.

The benefits consultant surveyed 661 companies this month and found that 94 percent of those that responded believe the law passed by Congress this year will raise costs. Eighty-eight percent plan to pass the increases on to employees, and 74 percent anticipate reducing health benefits and programs.

That could mean insurance co-payment or deductible increases or more high-deductible plans, said Mark Maselli, who heads Towers Watson’s North American Health and Group Benefits unit.

He added that companies will likely continue to offer “medical coverage that individuals are used to having” at least for the foreseeable future. Nearly three quarters of the companies responding to the survey said they expect to continue providing subsidized coverage for active employees.

Maselli said benefits could change as the law phases in over the next few years. But he saw no need for employees to panic.

“You’ve got coverage now, you’re likely to continue to have it through your employer, and it’s something you want to monitor over time,” he said.

Some companies could see small legislation-related cost increases next year, after the start of provisions that ban lifetime maximums for benefits and extend coverage of young adult dependents on parental plans to age 26. Maselli and other benefits experts say the size of this increase will depend greatly on the company and the employees it covers.

Towers Watson’s national survey spanned several industries and involved companies with a median size of 5,600 employees.

The survey also found that 43 percent of employers that offer retiree benefits expect to reduce or eliminate them.