Medicare Open Enrollment is Here. What to Know About Deadlines, Options and More.

The open-enrollment period goes from Oct. 15 to Dec. 7

Medicare open enrollment allows beneficiaries to review their health-insurance coverage and make changes.

Medicare's open-enrollment period officially starts on Thursday, allowing beneficiaries to adjust their health insurance plans or find new options altogether.

The open-enrollment period is an important time for all beneficiaries, even those satisfied with their insurance plans. It is an annual reminder to see coming changes to their current plan in the coming year, or to consider other medical needs for the near future, such as surgeries, procedures, new doctors or new medications.

Changes made during the open-enrollment period, which runs from Oct. 15 to Dec. 7, are effective as of Jan. 1 of the following year. Beneficiaries may have plenty of options to explore; the average Medicare beneficiary can choose among 35 plans in 2027, according to KFF, a healthcare-research firm. It is a decline from 39 plans the year before.

People often stick with the same plan for years just because it is familiar. More than a quarter (27%) of Medicare beneficiaries did not review their coverage options before or during the open-enrollment period this year, according to a new poll from the Institute for Healthcare Policy and Innovation at the University of Michigan. One-third of beneficiaries reviewed their options for less than an hour, and four in 10 reviewed for an hour or more, the poll found.

The wrong choice - or no choice - could cost thousands of dollars.

The open-enrollment period between October and December allows beneficiaries to switch between Original Medicare and Medicare Advantage, or vice versa. It is also when beneficiaries can join, drop or switch between Medicare drug plans or change their Medicare Advantage plans.

This is one of numerous enrollment periods

There are other enrollment periods to keep in mind.

One is the initial enrollment period, which occurs when a person turns 65. The initial enrollment period lasts seven months: the three months before the month the person turns 65 and the three months after.

Another is the general enrollment period, between Jan. 1 and March 31, when people who missed the deadline when they first became eligible for Medicare can sign up. Those who wait for this enrollment period may be subject to penalties. For example, eligible seniors who do not sign up for Part B may face a permanent penalty for enrolling late. The penalty is a 10% increase in premiums for each year coverage is delayed.

Another period is known as the special enrollment period, which must include a qualifying event. Eligibility for a special enrollment period includes losing qualifying health insurance, such as employer-sponsored plans or Medicaid.

There is also a separate open enrollment period for Medicare Advantage, which runs from Jan. 1 to March 31. Then, beneficiaries already enrolled in Medicare Advantage can change their benefits. It is not available for people who want to move from Original Medicare to Medicare Advantage.

-Alessandra Malito