U.S. employers are not the only ones looking at steep increases in medical plan costs next year. Costs are expected to increase by 10 percent worldwide, according to the 2025 Global Medical Trends report from Aon. The projected increase is nearly identical to this year's rate of 10.1 percent, which represents the highest increase forecasted in 10 years.

"Despite inflation projected to decrease in 2025, we expect health and well-being costs will continue to rise," said Kathryn Davis, vice president of global benefits for the professional services firm. "As a result, medical plans are an important concern for companies, especially those with a global footprint. Rising costs often bring unexpected budget increases and make affordability for employers and employees more difficult."

The Middle East and Africa are projected to have the highest trend rate of any region, at 15.5 percent. Asia-Pacific and North America will experience the highest year-over-year trend rate increases, at 11.1 percent and 8.8 percent, respectively. Rates in Latin America and the Caribbean and Europe are projected to increase by 10.7 percent and 8.9 percent, respectively—less than the projections for 2024 in both regions.