Turning 65: signing up for Medicare

Your Initial Enrollment Period

For most people the first chance to sign up comes at 65. Medicare calls it the Initial Enrollment Period, and it spans 7 months: three before your birthday month, that month itself, and three after. Signing up early in that window gets Part B started sooner.

Will you be signed up automatically?

If you already collect retirement benefits from Social Security or the Railroad Retirement Board, and started at least 4 months before turning 65, you are enrolled in Parts A and B automatically. Your Medicare card arrives in the mail about 3 months before coverage begins. If you are not receiving those benefits yet, you have to sign up yourself, through Social Security. Railroad workers and their spouses contact the Railroad Retirement Board instead.

Being enrolled automatically still leaves choices to make. Original Medicare does not include drug coverage, so you decide whether to add a Part D plan, a Medigap policy, or to choose a Medicare Advantage plan instead. Our Medicare Advantage vs Medigap guide lays out the trade-offs.

Still working at 65?

If you or your spouse are still working and have group health coverage through that job, Part B can often wait. You would then sign up later during a Special Enrollment Period that begins after your Initial Enrollment Period and lasts until 8 months after the job or the coverage ends, whichever comes first. Signing up in that window avoids the late penalty.

A few things catch people out. The 8-month window starts when you stop working, even if you keep COBRA or other coverage, so that coverage does not extend it. Retiree coverage may not count either: ask whether it is employer group health plan coverage, and if it isn't, sign up when you turn 65 to avoid a Part B penalty. Retiree plans may not pay if you don't have both Part A and Part B. And the window is about Part B; your drug coverage needs to be creditable too, or a separate Part D penalty can apply. Talk with the employer's benefits office about how its plan works alongside Medicare before you decide.

Missed the window?

If you miss your Initial Enrollment Period and no Special Enrollment Period applies to you, the next chance to sign up for Part B is the General Enrollment Period, from January 1 to March 31 each year. Coverage then starts the month after you sign up, and a lasting penalty may be added to your premium. Our guide to late enrollment penalties explains how it is figured.

Don't forget Medigap's own clock

If you plan to buy a Medigap policy, your 6-month Medigap Open Enrollment Period starts the first month you have Part B and are 65 or older. It happens once. See what Medigap is for why that timing matters.

Common questions

Last reviewed October 2026. Medicare rules, dates and dollar amounts can change each year; Medicare.gov has the official details.