And with half of all people on Medicare living on annual incomes of $24,150 or less, many can't afford the co-payments, co-insurance and deductibles associated with their coverage.
"In today's health-care climate, now is the time to seek solutions that make Medicare an even stronger, simpler and more affordable benefit," said Joe Baker, president of the Medicare Rights Center, which recently released a report examining the most common problems faced by those on Medicare.
For the report, the New York-based nonprofit group, which advocates for affordable health care for older adults and the disabled, analyzed more than 16,000 calls to its consumer helpline in 2015.
The group found that many callers had trouble maneuvering Medicare Part B, which covers outpatient medical care, including most doctor visits, and Medicare Advantage, which allows private health-insurance companies to offer Medicare benefits.
Affording their coverage and prescription drugs also proved challenging, with many having little to no savings on top of limited incomes. In 2014, half of all people with Medicare had $63,350 or less in savings, one in four had less than $11,900, and 8 percent had no savings or were living in debt, according to the Kaiser Family Foundation.
Every day, 10,000 Baby Boomers — people 51 to 69 years old this year — turn 65 and become eligible for Medicare.
Among other things, confusion can cause people to sign up late for Medicare Parts B and D, leading to hefty penalties, including some that can stick for life.
People have seven months to enroll in Medicare, starting three months before their 65th birthday month and extending for three months afterward.
If people are collecting Social Security benefits when they turn 65, they're automatically signed up for Medicare Part A, hospital coverage, and Part B. But if they haven't started collecting benefits, it's up to them to enroll, and missing the deadline can result in a lifetime penalty of 10 percent a year for each year they fail to enroll in Part B.
The rules can be especially confusing for people with employer-based health insurance. Those who are still working — and there are more older people working than ever before — can usually remain on their employer's insurance past 65 without penalty as long as they sign up for Medicare promptly after retiring. But retired workers still on company policies will be penalized for not signing up for Medicare once they turn 65.
One caller to the center's helpline who had elected COBRA coverage after being laid off unknowingly remained on the private health insurance beyond the short window he had to transition to Medicare. He learned he would likely receive a lifetime penalty for Part B and have to go several months without any kind of coverage for him and his wife, despite their medical needs.
Medicare Rights also fielded thousands of calls from people enrolled in Medicare Advantage plans, with questions about plan cost-sharing or how to switch plans or appeal a denied claim.
Another concern, the nonprofit group said, is the high number of people who must leave their pharmacy without their medications because of high costs and coverage denials. Too many are just out of range for the federal government's low-income subsidy, called Extra Help, and must choose between buying their medication or food.
Despite the challenges, "people don't have to feel alone" when trying to figure out Medicare, said Andy Haggard, Medicare outreach manager for the Central Ohio Area Agency on Aging.
Last year, the agency helped 977 central Ohioans with their Medicare questions through in-person or phone consultations. It also helped dozens of others at health fairs and Medicare workshops.
Over the past 12 months, the state assisted 340,000 individuals in one-on-one sessions and more than 1 million at group presentations, said Chris Reeg, director of the Ohio Senior Health Insurance Information Program.
Even current recipients who are satisfied with a plan should shop around each year to prevent any surprises, such as a co-payment increase or the elimination of coverage for certain drugs, she said.
In the past year, the state information program helped Ohioans save nearly $29 million by identifying more cost-effective plans and identifying people eligible for the Extra Help subsidy.