Employers will spend an average of $693 per employee on wellness-based incentives in 2015, up from $594 in 2014 and $430 five years ago, according to the latest survey about wellness programs from Fidelity Investments and the National Business Group on Health (NBGH).

Many employees aren’t taking full advantage of these programs and earning all of their incentives. Fewer than half (47%) of employees earned their full incentive amount in 2014, while 26% earned a partial amount. Together, this translates into millions of dollars of unclaimed incentives.

“The next challenge for companies is to continue to find ways to increase participation in these programs and encourage employees to earn the full incentive amount available to them, which will contribute to their financial well-being as well as their physical health,” says Robert Kennedy, Health and Welfare practice leader with Fidelity’s Benefits Consulting business in Boston.

“It starts with design and using data to be sure programs are relevant and match the needs of employees,” Kennedy tells PLANSPONSOR.

He says incentives will get some employees engaged in the programs, but beyond that, communications play a strong role. “Communications should set the context for employees—explaining why the employer is offering the programs and what it hopes to accomplish.”

Kennedy suggests frequent, short reminders about how to take advantage of incentives, using a variety of channels—emails, the employer’s intranet site or employee meetings. Short messages should contain a click-through for more detail for those employees who want it. Timing of messages is also important. For example, Kennedy says, if the employer offers a program in which employees can earn incentives quarterly, reminders should be sent well before the end of each quarter.

The programs should be easy to access, easy to use and fun for employees, according to Kennedy. He suggests individual activity challenges or team challenges. He adds that employers should gather feedback along the way from program participants as well as those not participating. This can provide success stories to share or suggestions for changes to programs.

“We’re seeing these programs start with the goals of improving health and managing cost trends, but increasingly they are becoming part of employers’ value propositions,” Kennedy says. “So incorporating communications about incentive-based health improvement programs in meetings about other key messages—such as employee town halls—can help create a culture of improving health.”

The Fidelity/NBGH survey found that, of the 79% of employers that offer health improvement programs, larger companies, with more than 20,000 employees, are spending the most on these programs; the per-employee average climbed to $878, up from $717 in 2014. The average for companies with between 5,000 and 20,000 workers rose to $661, up from $493 in 2014.

While employers are increasingly using incentives—such as cash, gift cards, reduced health care premiums or a contribution to a health care account—to encourage employees to participate, the use of disincentives among employers for not participating in these plans is decreasing.

The three most popular incentive-based health improvement programs for 2015 are biometric screenings (72% of employers plan to offer this program), health risk assessments (70%), and physical activity programs (54%). Among the top three, only 6% plan to use disincentives for not taking a health risk assessment, and 5% will use disincentives for not getting a biometric screening—down from 11% and 12%, respectively. No employers plan to use disincentives for not participating in physical activity programs, although 17% of employers continue to attach disincentives for not participating in smoking cessation programs.

The survey is the latest in a series Fidelity and NBGH have conducted since 2009.