ST. PAUL — Minnesota’s Department of Human Services fails to adequately verify the eligibility of people who enroll in public health care programs through MNsure, the state’s health insurance exchange, the state’s legislative auditor reported Wednesday.

The nonpartisan Office of the Legislative Auditor found several instances where the department paid for benefits to people enrolled in Medical Assistance and MinnesotaCare who weren’t eligible because their incomes were too high or other errors and suggested that the problem is widespread.

The agency also found that DHS failed to bill MinnesotaCare recipients for premiums for the first three months of 2014, then billed many for incorrect amounts afterward. The department also failed to terminate some recipients who failed to pay their premiums.

Medical Assistance, the state’s version of Medicaid, and Minnesota Care, which serves the working poor who don’t qualify for Medical Assistance, account for more than 315,000 of the nearly 371,000 signups through MNsure since the site launched in October 2013. The state paid $376 million in benefits for newly enrolled recipients in these programs through April.

“We understand that the state of Minnesota has ventured into one of the most complex, important and frankly expensive implementations of policies that we have ever done in the development of an insurance exchange. … And the road has been rocky indeed,” Legislative Auditor James Nobles told the House-Senate MNsure oversight committee.

The auditor’s office tested a small, random sample of 100 cases covering 193 enrollees, finding that nearly 17 percent were ineligible for the programs in which they were enrolled, resulting in payment errors. Deputy Legislative Auditor Cecile Ferkul told the panel there’s no way to be sure if it’s accurate, but that the finding would project out to about 28,000 people in the wrong program. She said some weren’t eligible for any public programs, while others might have been eligible for a different program.

“Had they been in a different program the cost to the state might have been different, and the services that they received might have been different,” Ferkul said.

Human Services Commissioner Lucinda Jesson wrote in a formal response that her department continues to work on fixing the problems, which cropped up in late 2013 and early 2014 as a new eligibility system was rolled out under tight timelines.