Nearly one in five midsize and large U.S. employers plans to reduce their part-time staffers' hours in order to minimize exposure to coverage mandates under the health care reform law, according to research by the Society for Human Resource Management.

Beginning in 2014, employers with at least 50 full-time workers — defined as employees working 30 hours or more per week — will be required to offer health benefit plans to 95% of their qualifying employees under the Patient Protection and Affordable Care Act or else incur a $2,000-per-employee tax penalty.

According to a pair of reports on the impact of the health care reform law released on Friday, 18% of companies with between 500 and 2,499 employees plan to scale part-time schedules to less than 30 hours per week to mitigate the costs associated with an influx of new members to their group health benefit plans. Additionally, 19% of large firms with 2,500 to 24,999 employees plan to reduce part-timers' hours, SHRM's research indicated.

Although more small employers — companies with less than 500 employees — anticipate double-digit increases to their health care costs in 2014 than larger firms do, SHRM's study noted that small employers were far less likely to cut their part-time staffers' hours as a response to the coverage mandate under the health care reform law.

Only 5% of employers with fewer than 100 workers plan to reduce part-time hours, even as 38% of the same group of employers expects their health care costs to increase by 16% or more when the coverage mandate takes effect next year.

%%BREAK%%

Similarly, 26% of companies with between 100 and 499 employees expect health care costs to grow by 11% to 15% in 2014, but only 9% of those firms say they will reduce part-timers' hours as a means of minimizing the increases, SHRM's research indicated.

While the potential for savings is substantial, benefits experts say employers should not let the desire to rein in health care costs blind them to the potential business and regulatory risks of making sudden, drastic changes to their staffing strategies. You can read the full SHRM report here.