Allina Health System says it’s going out-of-network next year with Medicare Advantage plans from Humana, a move that impacts about 17,000 people who have coverage from the health insurer and get care at Allina hospitals and clinics.

The Minneapolis-based nonprofit health system notified patients last month that it was considering the move due in part to claims denials and prior authorization requirements by the Kentucky-based health insurer. On Friday the change became official, as Allina started sending letters to affected patients.

With the change, Allina says it won’t let patients with Humana Medicare Advantage coverage schedule appointments at the health system next year.

“We negotiated in good faith with Humana over the past several months to remain a participating provider in their Medicare Advantage network,” Allina said in a statement. “Unfortunately, Humana was unwilling to agree on a new, fair contract. ... This change does not apply to Humana’s pharmacy plans or members of group retiree plans.”

Humana, one of the nation’s largest Medicare Advantage companies, said in a statement that the health system’s demands “overlook the value that Medicare Advantage plans provide.”

“We remain open to renewing a contract with Allina that is fair and beneficial for both parties,” the insurer said. “If our members have questions or need personal assistance, we encourage them to call the Humana Customer Care phone number on the back of their membership card.”

The decision provides a measure of clarity for seniors who have until Dec. 7 to decide whether they should switch health plans for next year. Those who already picked a 2025 plan can still go back and change it. There’s also a separate Medicare Advantage open enrollment period that runs January through March.

Medicare Advantage is a privatized form of Medicare coverage where seniors opt to receive their government-backed benefits through a private managed care health insurer.

Allina became the fifth health system with operations in Minnesota to announce it will drop from Humana’s network in 2025, following announcements from Avera Health, Essentia Health, North Memorial and Sanford Health.

Seniors in Minnesota this year have seen a wide variety of threatened disruptions in the Medicare Advantage market, including announcements by Essentia and HealthPartners that they would go out-of-network next year with Minnetonka-based UnitedHealthcare.

In those instances, United and the health systems reached agreements earlier this month so the providers will remain in-network for 2025.

Open enrollment runs Oct. 15 through Dec. 7. The Medicare Plan Finder tool is available online at Medicare.gov. The federal government assists consumers over the phone at 1-800-MEDICARE (1-800-633-4227). Health insurance agents can help individual seniors, as well. Minnesota seniors can get help exploring options by calling the state’s Senior LinkAge Line at 1-800-333-2433.