Premiums for individual plans on Maine’s Affordable Care Act marketplace would increase by an average of 16.8% in 2027 under proposals filed by insurers this week.

The Maine Bureau of Insurance is expected to approve the final rates in August. Last year, insurers proposed an average 24.2% increase, which was scaled back slightly to 23.9% for 2026 plans. Enrollees in small-group plans are facing an average increase of 15.7% next year, according to the filings.

Most ACA enrollees are shielded from the bulk of the premium increases because when premiums go up, the tax credits that help pay for them also increase.

However, some ACA plan recipients now shoulder the full cost of rate hikes because Congress failed to extend some of the tax credits that enrollees were receiving. Enhanced Premium Tax Credits, first approved in 2021 during the Biden administration, expired at the end of last year. Another set of tax credits, called Advance Premium Tax Credits, were part of the original law and do not expire.

Failing to extend the enhanced credits fueled large premium increases for thousands of Mainers and declining ACA enrollment this year. Premiums increased an average of 77% for 2026 because the enhanced tax credits expired, according to the Maine Office of the Health Insurance Marketplace.

Enrollment declined from about 65,000 in 2025 to 58,000 in 2026, with Maine officials estimating that about 3,500 people dropped their plans because they could no longer afford the premiums.

Kristina Lunner, deputy commissioner for the Department of Professional and Financial Regulation, which is in charge of the Maine Bureau of Insurance, said in an emailed response to questions that the expiration of the credits is one factor leading to higher premiums.

She said insurers are also pointing to overall inflation, and “increasing medical costs and utilization, with more utilization of expensive medical technologies, and expensive specialty medications.”

Lunner said insurers told the bureau that claim costs are coming in higher than expected in 2026.

After rates are finalized this summer, open enrollment for 2027 plans will begin on Nov. 1 at coverme.gov.

Jim Turner, spokesperson for Anthem insurance, said in a statement that the “largest impact on 2027 rates in Maine is higher hospital and prescription drug costs.”

Turner said that with shrinking ACA enrollment, “the remaining population tends to be less healthy, needing more care overall. So, a smaller population overall is paying for greater healthcare costs.”

Anthem insurance premiums on the individual market would jump by an average of 17.9%. The other two insurers on the individual market — Harvard Pilgrim and Community Health Options — are requesting average rate hikes of 9.2% for Harvard Pilgrim and 20.9% for Community Health Options. Mending Health, an insurer that offered plans for 2026, withdrew from the Maine ACA market for 2027.

Kathleen Makela, Harvard Pilgrim spokesperson, said in a statement that the rate proposal reflects “expected increases in healthcare spending driven by rising prices and increased utilization.”

Theresa Miller, a spokesperson for Community Health Options, said in a statement that the agency is “facing the same cost pressures being felt across the entire healthcare system — by patients, providers and health plans alike.”