WARWICK — People employed by small businesses will soon be able to get comprehensive health insurance, including doctors’ visits, hospitalization, preventive services and drug coverage — for low premiums averaging just over $300 a month.

But there’s a catch. If you don’t want to pay through-the-roof deductibles ($5,000 for an individual, $10,000 for a family) before your coverage kicks in, you have to promise to be good.

That is, you have to get a primary-care doctor, undergo a health assessment, and follow the recommendations that emerge from the health assessment. Depending on what’s wrong with you, that could mean signing up for smoking-cessation or weight-loss classes, or participating in disease-management programs.

That’s the essence of the new low-cost “wellness health benefit plans” that Health Insurance Commissioner Christopher F. Koller unveiled yesterday.

Under a law passed last year, Blue Cross & Blue Shield of Rhode Island and UnitedHealthcare of New England must offer these plans to businesses with 50 or fewer employees starting Oct. 1. The premiums will vary from company to company but will average $322 for Blue Cross and $309 for United for a single person — about 18-percent lower than similar plans now on the market.

The wellness plans are expected to appeal to businesses on the verge of eliminating health-insurance coverage altogether because of high premiums. Koller said he expected 5,000 to 10,000 people to enroll (of the roughly 116,000 who work in small companies) but no minimum number is needed for the plans to succeed. Each insurer is allowed to cap enrollment at 5,000.

“We don’t think this will be for everybody,” Koller said. “We’re asking individuals to make a commitment. That’s different.”

In negotiating the plans, Koller and an advisory committee used a touch of social engineering. The plans offer incentives for good health and appropriate use of the health-care system. In theory, these measures should lower medical expenses, whose soaring costs are the main reason for increasing premiums.

“The real issue is, what can we do to slow down the inflation of health-care costs?” said Governor Carcieri at a news conference announcing the plans yesterday. “There are things that each of us can do that will delay the onset of disease.”

“What makes this plan unique,” Koller said, “is the benefit design that really says to people, ‘There is no free lunch.’ ”

For example, in addition to lower deductibles and smaller co-pays for those who pledge “wellness,” the plans fully cover annual physicals, mammograms and prostate-cancer screenings without applying the deductible. But you pay through the nose — $200 per visit — if you go to a hospital emergency room with a problem that does not lead to being admitted.

The commissioner and his Wellness Advisory Committee, composed of small employers, brokers, consumer advocates, union leaders and others, also refused to accept as “low cost” any plan that had low premiums but lots of other costs, such a high co-payments and deductibles. In this way the state sought to give small businesses the same clout that larger businesses have in negotiating with insurers.

Blue Cross and United will each offer two plans with the same premium — a “basic plan” and an “advantage plan.” The “advantage” plan will have lower deductibles, lower co-pays and lower out-of-pocket maximums.

In the first year, “advantage” participants have to pledge to participate in a wellness program if it’s deemed necessary. In the second year, they have to actually demonstrate that they followed the recommendations. That is, if you’re advised to enroll in a weight-loss program, you have to show that you went to the classes, but you don’t have to prove that you actually lost weight. Further details on how the insurers will police the wellness components have yet to be developed.

But Koller said he expected the biggest medical-cost savings to come, not from the weight loss and antismoking aspects, but from the disease-management programs. Such programs, which most insurers already offer to large businesses, help people with chronic conditions such as diabetes or asthma to monitor and control their illnesses, preventing costly hospitalizations and other catastrophes.

“Twenty percent of the people drive 80 percent of the cost,” Koller said.

But Koller acknowledged that the wellness health-benefit plans could become a magnet for those who are already healthy, trim and nonsmoking.

The aspect of the plans that may prove thorniest hasn’t been worked out and won’t go into effect until Jan. 1, 2009: a requirement for financial incentives encouraging patients to choose health-care providers whose care is deemed high-quality and efficient. For example, co-pays might be lower if you choose a doctor in a network of physicians who meet the insurers’ standards. The contentious part will be finding meaningful ways to measure the quality of the care that doctors provide.

Additionally, a similar plan will eventually be developed for individuals, such as self-employed people, who buy insurance on their own rather than through a group.

The law establishing the plans required that the average annualized premium equal no more than 10 percent of average annual wages in Rhode Island. The law also required incentives for insurers and enrollees to focus on primary care, prevention and wellness, to control chronic illnesses, to use the lowest-cost appropriate setting for care (such as a doctor’s office rather than an emergency room) and to choose evidence-based quality care.

The Wellness Advisory Committee, which first convened in August, devised the detailed requirements for the plans. Insurers submitted their proposals on Jan. 12, and after getting feedback from the committee and the commissioner, they submitted their “best and final” proposals last month. This week, the commissioner issued his final order, which required the plans to make further changes to their best proposals.

Because they had received the final order only late Monday, neither United nor Blue Cross had much to say about how their plans would work. Blue Cross did not send a representative to Koller’s announcement and declined to comment.

Jason C. Martiesian, United’s director of government relations, who attended the announcement, said afterward, “I think it’s going to work.”

But he noted that the wellness measures may actually cost money rather than saving it, because they will draw people into new services. Will that save money in the long run? “Possibly,” he said.

Asked whether the plan would be a hard sell, he said, “It’s going to be a different sell. There’s a commitment that needs to be made.”

Donald R. Nokes, a member of the Wellness Advisory Committee, whose business, NetCenergy, hosted the news conference, said he intended to offer one of the wellness plans to his employees. He couldn’t predict how much money he might save in premiums. But he said he mainly supported the concept of “pulling the consumer into the process” to take responsibility for the cost of care.

“Maybe I’m being idealistic,” Nokes said. “The alternative clearly isn’t working.”

For more details on the plans, go to www.dbr.state.ri.us/divisions/healthinsurance/

ffreyer@projo.com