The average cost of employer-sponsored health plans is surging--hitting its highest annual spike in more than a decade, with small businesses bearing the brunt of the burden.

A Monday survey released by the asset management firm Mercer reveals that the average cost for employer-sponsored health insurance climbed 6.3 percent in 2021, nearly double that of last year's 3.4 percent uptick. That's the cost equivalent of $14,542 per worker for U.S. health plans with 50 or more employees, according to the survey. 

It's also the largest annual cost increase since 2010. 

The reason for the climb? Most employers believe workers are simply seeking out care again, after putting off procedures during the early part of the pandemic, according to Mercer's Sunit Patel, the company's chief actuary. Patel added in a statement that costs could climb further in the future as a result of inflation, long Covid-19 claims and even more "catch-up care." 

Small businesses employing 50 to 499 workers endured sharper cost increases, at 9.6 percent, compared to an average uptick of five percent among larger companies.

Smaller employers are usually fully insured and increases are driven by insurance company expectations, which explains why they were hit with a higher increase, according to Mercer's Tracy Watts, who serves as the national leader for U.S. health policy at the firm. Larger firms tend to be self-insured, in which a business is responsible for covering the costs for health benefits offered to workers by paying a claim directly--thus they tend to have more control over costs. 

"Some employers in that size category have moved to a hybrid funding approach for more control, but [that] can also mean more risk with the unknowns we are facing on the longer term impact of the pandemic and future cost trends," Watts tells Inc. 

Still, most employers chose not to raise deductibles. For small businesses, median deductibles for individual coverage on a preferred provider organization (PPO) plan dipped from $1,000 to $900 this past year. 

Attractive health benefits can help lure in new talent and also retain current workers, Watts says. "The tough challenge of solving for both health care cost and health care affordability means maximizing value and accepting the disruption it may bring," she adds.