Medicare General Enrollment Period: The Jan., March Deadline

The Medicare General Enrollment Period (GEP) runs from January 1 through March 31 every year. It exists for people who missed their Initial Enrollment Period for Medicare Part A and/or Part B and don't qualify for a Special Enrollment Period. If that describes your situation, the GEP is your once-a-year chance to sign up, and missing it can mean waiting another full year for coverage plus a lasting late enrollment penalty.

Who Actually Needs the General Enrollment Period

Most people get Medicare automatically or sign up during their seven-month Initial Enrollment Period around age 65 without issue. The GEP matters specifically for people who:

• Turned 65, became eligible for Medicare, and simply didn't enroll in Part A and/or Part B on time
• Had coverage through a small employer or other source that Medicare does not treat as creditable coverage, so no Special Enrollment Period applies
• Let their Special Enrollment Period expire, for example, more than eight months passed after leaving job-based coverage, without enrolling

If you're still working past 65 with coverage through a large employer, or your spouse's employer, you likely don't need the GEP at all. In that case, review how employer insurance interacts with Medicare enrollment or read about enrolling in Medicare when you retire, since you'll typically get a Special Enrollment Period once that coverage ends instead.

When Your Coverage Starts

If you enroll during the General Enrollment Period, your Medicare coverage begins the first day of the month after you sign up. This is a meaningful improvement from the rule in place before 2023, when coverage under the GEP didn't start until July 1 regardless of when in the January-March window you enrolled. According to Medicare.gov, this faster start date now applies to anyone who signs up during the GEP, closing what used to be a coverage gap of several months.

Because the start date is now tied to your enrollment month, signing up early in January still gets you covered sooner than waiting until the March 31 deadline. There's no advantage to waiting once you know you need to enroll.

The Cost of Waiting: Late Enrollment Penalties

Enrolling through the GEP instead of your Initial Enrollment Period can trigger a Part B late enrollment penalty. According to Medicare.gov, your Part B premium can increase 10% for each full 12-month period you were eligible for Part B but didn't enroll and didn't have other creditable coverage. This penalty is added to your monthly premium for as long as you have Part B, it isn't a one-time fee.

Part A also carries a penalty, but only if you have to pay a premium for it (most people don't, since they qualify for premium-free Part A based on work history). If you do pay a Part A premium and delay enrollment, your premium can rise 10% for twice the number of years you could have had Part A but didn't.

If you're unsure whether your prior coverage counts as creditable and protects you from a penalty, see this guide to Medicare creditable coverage before assuming you need the GEP at all.

What Happens After You Enroll

Once you sign up for Part A and/or Part B during the General Enrollment Period, you get a separate window, April 1 through June 30, to choose a Medicare Advantage plan or a standalone Part D prescription drug plan. This follow-on period exists specifically for people coming out of the GEP, since they couldn't select those plans without Original Medicare in place first.

If you're brand new to the enrollment process altogether, the broader overview at how to enroll in Medicare walks through each enrollment window, including the GEP, in context. And if you're not yet 65 but have a qualifying disability or conditionMedicare eligibility under 65 explains how your enrollment timing may differ.