Employers that want to make significant changes to their health benefit programs must tread very carefully. Employees are generally very happy with their health benefit programs and those programs figure prominently in employee decisions about whether they join or leave an employer.

These are among the findings of a survey of 1,545 employees at 350 large organizations with 2,000 or more employees conducted last spring by the National Business Group on Health (NBGH) in Washington, D.C. Here are more of the key findings:

Employees value their benefits… It will probably come as no surprise to employers that 87% of employees rate their health benefits as very important when making a decision about accepting a new job or remaining with their employer. (For the record, 78% also rated retirement benefits as very important, which is up sharply from 63% in 2007.) “For employers that want to compete for talent in tough labor markets, especially when it is a challenge to find people with the right skill sets, good health benefits are essential,” says NBGH CEO Helen Darling.

“We asked employees about their level of satisfaction with health coverage, what they like the most and what is most important to them,” says Darling. “The number one thing for employees is making sure that they have very good coverage for serious illness. Most large employers have very comprehensive coverage in those circumstances so they need to help employees and family members understand that they have good protection for serious illness.”

…but they don’t know the value of their benefits. When it comes to understanding the monetary value of their benefits, 62% of employees are unable to estimate how much their employers pay for their health benefits. When asked to estimate employer costs for individual health benefits, 23% of the respondents estimated that their employers pay $500 dollars a month for their coverage. Considering that the average employer pays $9,000 per employee, these employees’ estimates are off by about $3,000 per year. “Employers need to help their employees understand how rich the benefit is that they are providing,” says Darling.

Employees want to keep premiums low. A growing number of employees want their health insurance premiums to remain as low as possible. Back in 2007, 27% of employees preferred a low premium above all; now, 54% prefer a low premium. “People are beginning to pay more attention in every way to cost,” says Darling. “They want a reasonable premium and reasonable out-of-pocket costs for doctor visit.”

Employees do not think it is fair to tie health status to premiums and other costs. The majority of employees (68%) do not believe they should be required to participate in a wellness program in order to qualify for health insurance. Moreover, 71% do not think employers should charge employees more for health coverage if those employees don’t meet specific health goals.

Employees are not confident shoppers. Employers that harbor hopes that they can incorporate public or private health insurance exchanges in their benefit designs in order to allow employees to choose their own health plans need to prepare employees carefully for their new role as health insurance shopper. A significant portion of employees (37%) are not confident in their ability to shop for health insurance on their own, and 53% are not confident that they could purchase the same or better quality insurance on their own.