A new law requiring private insurers to cover the cost of hearing aids is causing confusion over who can benefit from the mandate.

The law took effect Wednesday, making Maine just the fifth state to require the coverage. It calls for insurers to cover the cost of hearing aids up to $3,000 per ear every three years for people with documented hearing loss.

But Maine’s new law carves out exemptions, including one for companies that are self-insured. Most large corporations, including MaineHealth, the state’s largest employer, self-insure for health care coverage because it is generally less expensive. The Portland-based hospital operator and health care provider is the largest employer in Maine, with more than 18,000 employees, according to state labor data.

Andrea Guptill of Bristol, an employee of MaineHealth, said she was enthused about the new law because she thought it meant that insurance would cover the $5,400 cost of hearing aids for her husband, Kim Guptill, 59. Kim Guptill is disabled, in part because of hearing loss, Andrea Guptill said.

“It sounds great on paper,” said Andrea Guptill, who learned of the new coverage requirement this week. “I saw this the other day and thought, ‘Maybe there’s a reason we didn’t come up with all this money” before now.

But “they have already found a way around this,” she said, referring to the exemption for self-insurers.

Maine, like most states, has limits on what it can require insurers to cover. For the most part, its power is limited to state-regulated plans, including plans covering government employees, and association plans that typically cover employees of multiple companies often within the same industry.

National programs, such as Medicare, are governed by the federal government and are unaffected by a state mandate. That means the new hearing aid requirement won’t apply to most Mainers 65 or older who rely on Medicare for health care coverage. Hearing aids also aren’t covered by Medicare supplement plans, which many people over 65 buy to cover part of the cost of health care that’s not covered by Medicare.

State officials said they expect about 6,000 Mainers will be eligible for hearing aids covered by insurers. The amount of the benefit will be governed by an insurer’s rules, such as whether a deductible has been met and if the provider is part of the insurer’s network.

But that’s well below the roughly 10,200 older Mainers in the workforce with disabling hearing loss, said Jess Maurer, the executive director of the Maine Council on Aging.

She said more than 120,000 Mainers 55 to 64 years old are in the workforce and about 8.5 percent of them, or 10,200, have disabling hearing loss.

“Remarkably, only about 20 percent of older people with significant hearing impairment obtain hearing aids,” she told the legislative committee that handled the hearing aid bill.

The gap between those who need hearing aids and those who get them is “staggering,” she said. “Somewhere between 20 (million) and 35 million Americans need hearing aids, while only about one-quarter of that number actually get them.”

Previously, Maine law required insurers to cover the cost of hearing aids only for children younger than 18, and the insurers’ costs were capped at $1,400.

The new hearing aid mandate is estimated to add $5.64 to insurance premiums annually. Most insurers built the anticipated cost into the premiums for their plans that began on Jan. 1, said Eric Cioppa, Maine’s superintendent of insurance.

Despite the limitations, Cioppa said the law requiring coverage is a step forward.

“It’s pretty complicated, but you’ve gone from a small segment of the population to a much larger percentage” getting financial help for hearing aids, he said.

The Maine chapter of AARP also praised the requirement and noted the large number of Americans who need hearing aids, but don’t have them.

“The number one reason (people don’t have hearing aids) is the high cost of these devices and the lack of insurance coverage,” said Lori Parham, AARP’s state director in Maine. “Loss of hearing isn’t only frustrating, it carries with it health risks and has been linked to walking problems, falls and even dementia.

“The new law will have a positive impact in our state and enable residents with hearing loss to more fully participate in their communities and the workforce.”