This year's extra-long open enrollment period for seniors to enroll in Medicare Advantage health plans ends Sunday, which means now is the last chance for many to make changes.

Minnesota's Medicare market has undergone a large shift over the past six months due to a federal law that eliminated Medicare Cost health plans across 66 counties this year. More than 300,000 people were forced out of their health plans, and they faced a choice between original Medicare and Medicare Advantage plans sold by private health insurers.

The open enrollment period that ends Sunday is an important opportunity for those who enrolled in a Medicare Advantage plan for Jan. 1 and found they need to make changes.

"We're still hearing from beneficiaries that found out the plan that they changed into … did not cover their providers, or it did not cover their drugs or a combination of the two," said Kelli Jo Greiner, health policy analyst with the Minnesota Board on Aging.

Between Jan. 1 and March 27, the state's Senior LinkAge Line helped 3,221 people make coverage changes. The help line is not taking calls this weekend, but Greiner said: "People can call 1-800-Medicare and get help that way." The Medicare.gov website is available as well.

Through Sunday, beneficiaries can switch to a different Medicare Advantage plan that includes Part D prescription drug coverage, or they can drop their Medicare Advantage plan and return to original Medicare and enroll in a separate Part D plan for medicine coverage. Those who opt for original Medicare, however, could face health screening if they want to buy a Medicare Supplement policy to lower out-of-pocket costs with the government program.

Those who lost Cost plans had a special "guaranteed issue" right to Medicare Supplements without answering health questions that could block coverage, but the right ended earlier this month.

The regular Medicare open enrollment for 2019 ended Dec. 7. Beyond the special enrollment period that ends Sunday, some consumers may be eligible for other special enrollment periods through the end of the year, state officials said.

Medicare has become a big business for health insurers, and the shift with 2019 coverage set off a competitive frenzy among insurance companies in Minnesota.

In 2017, carriers across the country saw about $29.9 billion in premium revenue from Medicare Supplement plans, according to Mark Farrah Associates, a Pennsylvania-based market research firm. The company has data on roughly three-quarters of the Medicare Advantage market and says those insurers in 2017 saw about $171 billion in revenue.

Christopher Snowbeck • 612-673-4744

Twitter: @chrissnowbeck