WASHINGTON—Final health care reform-related regulations will require many employers to expand their coverage of preventive services and tests.

The regulations, issued last week by the departments of Health and Human Services, Labor and Treasury, provide guidance on a provision in the health care reform law that will require group plans to provide full coverage, with no employee cost-sharing—such as through deductibles, copayments or coinsurance—for preventive services and tests.

The requirement takes effect Jan. 1, 2011, for employers with calendar-year health care plans. So-called grandfathered plans, though, will be exempt from the new coverage mandate. To retain grandfathered plan status, employers can't, among other things, boost coinsurance requirements or raise the percentage of premiums paid by employees by more than five percentage points.

Under the health care reform law and the regulations, no employee cost-sharing can be required for tests and screenings recommended by the United States Preventive Services Task Force, an independent panel of health care experts.

Among other things, no employee cost-sharing would be allowed for blood pressure, diabetes and cholesterol tests, annual physicals, vaccinations, age-appropriate colonoscopies, as well as obesity and smoking cessation counseling.

Many employers already provide full coverage, or close to that, for preventive services, though not for the entire range of preventive services and tests that they will have to provide at no cost, said Mike Thompson, a principal with PricewaterhouseCoopers L.L.P. in New York.

Coverage is provided, though not necessarily at 100%, noted Jim Winkler, a principal in the Norwalk, Conn., office of Hewitt Associates Inc.

While 100% coverage will have to be provided for preventive services, the regulations make clear that comparable coverage does not have to be provided for preventive services delivered by out-of-network providers. The law was not clear on that point, experts said.

On average, the new mandate will boost, at least initially, group health care costs by 1.5%, as more health plan enrollees get preventive services and tests, federal regulators say.

Down the road, though, if those tests help identify medical problems before they develop into expensive-to-treat conditions, the growth in health care expenditures could be slowed.

“The reality is that preventive care services can be very cost effective,” said Dr. Jeff Levin-Scherz, a consultant in the Boston office of Towers Watson & Co.