Medicare Eligibility Calculator: When Can You Sign Up?

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How the windows work

Medicare eligibility age. Medicare eligibility begins at 65 for most people (younger people can qualify after 24 months of Social Security disability benefits, or with ALS or end-stage renal disease). Your Initial Enrollment Period is the seven-month window that starts three months before the month you turn 65 and ends three months after it.

Part A is hospital insurance. For most people it is premium-free and can be taken at 65 even if you keep working. Part B is medical insurance; it has a monthly premium and, if you delay it without qualifying employer coverage, a late-enrollment penalty that lasts as long as you have Part B.

Read next: Initial Enrollment Period and turning 65, the turning 65 checklist, and Special Enrollment Periods.

Frequently asked questions

Do I have to sign up for Medicare at 65?

You do not have to, but signing up late for Part B can mean a permanent late-enrollment penalty unless you have qualifying coverage through an employer. Part A is premium-free for most people, so many people take Part A at 65 even when they delay Part B.

What if I am still working at 65?

If you have group health coverage through an employer with 20 or more employees (yours or a spouse’s), you can usually delay Part B without a penalty and sign up during a Special Enrollment Period when that coverage ends. Coverage from an employer with fewer than 20 employees usually does not protect you from the penalty.

What if I missed my window?

You can sign up for Part A and Part B during the General Enrollment Period, January 1 through March 31 each year, and coverage begins the month after you enroll. A Part B late-enrollment penalty may apply.

Researched and reviewed by Jordan Diaz, Licensed Insurance Agent, NPN 18910035, Senior Benefit Assistance. This page does not display plan data; the plan figures elsewhere in this section come from CMS’s published CY2027 Landscape Source File, data as of October 18, 2026. Last reviewed: October 26, 2026.