Finances for Community Health Options got a bit cloudier in May, but the cooperative health insurer is still on target overall with its plan to stabilize finances, the Maine Bureau of Insurance said Wednesday.

The bureau is closely monitoring the finances of the Lewiston-based insurer after it posted a $31 million loss in 2015, a year after being the only insurance cooperative set up under the federal Affordable Care Act to turn a profit. The agency publishes monthly reports on Community Health Options’ performance.

The cooperatives are intended to provide competition so that for-profit and established insurers don’t dominate the health insurance market. Community Health Options is a nonprofit that provides coverage to nearly 83,000 people, about 85 percent of whom live in Maine, with the rest in New Hampshire.

In its latest monthly statement, the bureau said the net loss in May was 25.7 percent worse than the target set in a plan to help keep the cooperative’s losses within a $43 million reserve fund. The fund was established last year to help the cooperative avoid another big loss in 2016. Through the end of May, the draw-down from that reserve was 6.1 percent less than projected in the plan.

Community Health’s portion of a cost-sharing agreement was $4.4 million higher than had been anticipated, but that was partially offset by higher payments under reinsurance and risk adjustment programs. The bureau said the overall impact on the insurer’s finances is still being evaluated and will be analyzed more completely when the cooperative issues its quarterly financial statement for the three months that ended June 30.

The bureau also said that paid claims and incurred claims were higher than planned for May, but year-to-date figures for both those categories are still slightly below the cooperative’s financial plan. Total expenses for May were nearly 10 percent lower than the financial plan, and year-to-date expenses are 4.7 percent lower.

“Notwithstanding the … losses in May, (Community Health’s) reported (year-to-date) results through the first five months of 2016 were generally consistent with its plan,” the bureau said.

Last year, the cooperative had a profit of nearly $23 million in its first quarter, but losses began to accrue during the summer and accelerated as the year went on.