While most employee benefits get pricier, group life insurance has become more affordable.

“It’s the only employee benefit that I know of where the cost has actually continued to go down,” said Matthew Purington, Portland, Maine-based assistant vice president of product and market development with Unum Group. “People are living longer, and frankly, companies are paying less as a result in death claims.”

For an employer to provide $50,000 of life insurance to their employees, it often costs less than $100 per worker, Mr. Purington said, adding that it varies by industry and demographics of the group. And for employees to buy voluntary life insurance, “they can obtain anywhere from $100,000 to $250,000 of insurance depending on their age for a couple of hundred dollars per year,” he said.

That low cost, along with the need for employers to manage costs, has caused the popularity of voluntary life products to surge.

According to LIMRA International Inc., for instance, voluntary term life sales increased by 18.1% in the first six months of 2015 from the same period the year before. In comparison, in the first half of this year, basic term life sales increased 0.1% from the year-ago period.

In the past, employers offered life coverage that totaled two or three times an employees’ annual salary, but today, many offer coverage in the amount of only the annual salary, said Steve Schreiber, Wellesley, Massachusetts-based director of product management with Sun Life Financial Inc. Other employers have cut back to offering a flat $50,000 life insurance policy to prevent tax implications for the employee, he said.

Anything the employee pays for, on the other hand, is not taxed, said John Ehrlich, Atlanta-based national lead consultant for group life and accident at Towers Watson & Co. He said about 40% of an employer’s workers will enroll in voluntary life insurance programs.

“It’s a very low-cost benefit compared to something like medical and hopefully has a high impact compared to its cost,” Mr. Ehrlich said as one reason employers offer life insurance to their workers. “It really gets down to financial well-being — to the extent that employees can be freed from some financial stress, it has been shown to have an impact on productivity as well as absenteeism.”

But it’s not always about costs. “Employers value the benefit because employers are the first people that often hear about the death of an employee or an employee’s spouse, and employers grieve, too,” said Von Peterson, senior vice president of group insurance life insurance with Securian Financial Group Inc. It’s “very important to the employer (that) their people are protected by life insurance.”