If you do nothing during Medicare Open Enrollment (Oct 15 - Dec 7), your current Medicare Advantage (Part C) or Part D drug plan will generally auto-renew for the next year, continuing your coverage uninterrupted as long as you keep paying premiums, but this can mean missing out on better plans or facing rising costs and benefits changes in your old plan. For Original Medicare (Part A & B), you don't need to do anything to keep it, just pay premiums; but for Part D, you should review options annually as drug formularies and costs change.
If you do nothing during the Medicare Open Enrollment period, your coverage under traditional Medicare plus stand-alone drug coverage, if applicable, will continue uninterrupted next year (assuming your stand-alone drug plan will continue to be offered).
If you miss Medicare's Annual Enrollment Period (Oct 15 - Dec 7), your current plan usually renews automatically for the next year, but you might miss opportunities to switch to a better Part C (Medicare Advantage) or Part D plan unless you qualify for a Special Enrollment Period (SEP) due to life events like moving or losing coverage, or use the MA Open Enrollment Period (Jan 1 - Mar 31) to change MA plans or return to Original Medicare. Missing your Initial Enrollment Period (around your 65th birthday) can lead to coverage gaps and late enrollment penalties for Part B unless you had creditable employer coverage.
During open enrollment, you can enroll in or make changes to health insurance, life insurance, dental insurance, and other employee benefits offered through your workplace or the government marketplace. These are some common adjustments you can make to your benefits during open enrollment: Enroll in new benefits.
Example: If you waited 2 full years (24 months) to sign up for Part B and didn't qualify for a Special Enrollment Period, you'll have to pay a 20% late enrollment penalty (10% for each full 12-month period that you could have signed up), plus the standard Part B monthly premium ($202.90 in 2026).
Here are some of the biggest Medicare mistakes to avoid:
Generally, you're first eligible to sign up for Part A and Part B starting 3 months before you turn 65 and ending 3 months after the month you turn 65. (You may be eligible for Medicare earlier, if you get disability benefits from Social Security or the Railroad Retirement Board.)
If you joined a Medicare Advantage Plan during your Initial Enrollment Period, you can change to another Medicare Advantage Plan (with or without drug coverage) or go back to Original Medicare (with or without a drug plan) within the first 3 months you have Medicare Part A & Part B.
Outside of open enrollment, cancellation is typically only allowed for life status change events. Examples include marriage, divorce, having a baby, leaving the company, or significant plan changes. Special enrollment periods may vary in length but generally allow changes within 60 days of the qualifying event.
Employees who feel their benefits are unclear or impersonal are less likely to trust their employer or feel supported at work. In short, when benefits feel confusing, they stop feeling like benefits at all. Or, as one employee might put it: “Open enrollment shouldn't feel like speed-dating your health plan.”
An open enrollment grace period isn't a standard time after the main window, but rather a short extension (often 30 days) that some employers or carriers offer to finalize selections, while missing enrollment typically leads to waiting for the next period or qualifying for a Special Enrollment Period (SEP) due to life events like marriage, a new baby, or losing other coverage.
If you already have an ACA plan, your insurance company may automatically renew it for the following year. This isn't the case in every state, however. But if you don't have coverage, you typically won't be able to enroll in a new plan until the next Open Enrollment Period—unless you qualify for a special circumstance.
If you're going back to work and can get employer health coverage that is considered acceptable as primary coverage, you are allowed to drop Medicare and re-enroll again without penalties. If you drop Medicare and don't have creditable employer coverage, you'll face penalties when getting Medicare back.
For each 12-month period you delay enrollment in Medicare Part B, you will have to pay a 10% Part B premium penalty premium penalty See Late Enrollment Penalty. , unless you have insurance based on your or your spouse's current work.
Medicare Premiums Over $500
However, if you have a higher-than-average income, your Part B premiums start going up on a sliding scale. How much extra you pay is based on the income you reported to the IRS two years ago.
Medicare open enrollment — your opportunity to choose a Part D prescription plan or Medicare Advantage plan for the next year — always ends Dec. 7. If you missed the annual sign-up period that starts Oct. 15, even by one day, you'll be automatically reenrolled in your current plan as long as it's offered in your area.
If you missed the Medicare open enrollment, which runs from October 15 to December 7 each year, you will be automatically re-enrolled in your current plan for the following year. If you want to change your coverage after December 7, you may not be able to do so, unless you qualify for a Special Enrollment Period (SEP).
California's penalty is based on income and family size. For 2026, the minimum fine is around $900 per adult and $450 per dependent child, unless you qualify for an exemption. The penalty may be higher for households with higher incomes.