The Medicare General Enrollment Period: Signing Up for Part B From January to March

You turned 65, you felt fine, and you let Part B go by. Now you want it, and the first window is shut. That happens to a lot of people. Medicare has a yearly route back in. It is called the General Enrollment Period. It runs from January 1 to March 31 each year. If you sign up in that window, your Part B cover starts the month after you sign up. This guide shows who the window is for, how to use it, and what a late start can cost. Our Paying for Care section holds more guides on Medicare costs and sign-up rules.

Who this window is for

Your first chance to sign up for Part B is your Initial Enrollment Period. It spans seven months around your 65th birthday. Some people miss it on purpose. Some miss it in error. Some worked past 65 with job-based cover and then lost the thread when the job ended.

A Special Enrollment Period can save some of those people. If you had group health cover from a job, yours or a spouse's, you can often sign up for Part B without penalty while you work or in the months right after the job or the cover ends. That path has its own forms and proof rules.

The General Enrollment Period is the route left when no other window fits. It does not ask why you missed your first chance. It opens each year on January 1 and closes on March 31. If you sign up in it, you wait for cover to start, and a late penalty may apply. But the door does open, each year, for anyone who missed out.

When coverage starts

The start rule changed in recent years, and old advice can mislead you. Medicare.gov states the current rule: if you sign up during the General Enrollment Period, your coverage starts the month after you sign up. Sign up in January, and your Part B cover starts February 1. Sign up in March, and it starts April 1.

That start date matters for care you have planned. A surgery set for the same month you sign up is not covered by the new Part B. If you can, sign up in January. It gives you the earliest start and the shortest gap.

Until your Part B starts, you pay the full cost of doctor care, tests, and other Part B services on your own. Part A, if you have it, still covers hospital care under its own rules. The gap is in the Part B side of your care.

What Part B costs once you are in

The standard Part B premium is $202.90 per month in 2026 (Ledger A1). Most people pay that amount. People with higher incomes pay more, under Medicare's income-based rates. The premium is most often taken out of a Social Security check.

Part B also has a yearly deductible of $283 in 2026 (Ledger A2). You pay that amount for covered care first. After the deductible, you most often pay 20 percent of the Medicare-approved amount for Part B services.

A late penalty can sit on top of the premium. If you could have had Part B but went without it, Medicare may add a penalty to your monthly premium, and you pay it for as long as you have Part B. The size turns on how long you went without cover. Our guide on the Part B late enrollment penalty shows how the math works and who is protected from it. Read it before you assume the worst. Some gaps do not count, such as months you had job-based group cover.

How to sign up in the window

• You apply through Social Security, not through Medicare. You can apply online at the Social Security site, by phone, or at a local Social Security office.
• Gather proof of your age and work history if asked. If you had job-based cover after 65, gather proof of that too. It can bear on the penalty.
• Apply early in the window if you can. A January sign-up starts cover on February 1.
• Ask for a written record of your application date. That date sets your start date.
• Once Part B starts, look at the rest of your cover. You will have a window to buy a Medigap policy or join a Medicare Advantage plan. Those windows have their own dates, so ask about them as soon as your Part B start date is set.

Who pays for what

• You pay the Part B premium of $202.90 per month in 2026 (Ledger A1), plus any late penalty that applies to you.
• You pay the Part B deductible of $283 for the year in 2026 (Ledger A2), then most often 20 percent of the Medicare-approved amount for covered care.
• Medicare pays its share of covered Part B services once your cover starts and the deductible is met.
• A Medigap policy pays toward costs Original Medicare leaves. It does not cover a service on its own. Your right to buy one without health questions can turn on when your Part B starts, so ask early.
• Medicaid, through a Medicare Savings Program, can pay the Part B premium for people who meet income and resource rules. Our guide on applying through your state shows how.
• Before your Part B starts, you pay the full cost of Part B type care yourself. No program backdates cover into the gap.

Sample situation

Sam is 67. He retired at 65 with no job-based cover and skipped Part B. He felt healthy and did not want the premium. This fall his doctor said he needs a heart test and closer care. Sam learned his Part B gap the hard way when a bill came in full. In January, he applies for Part B through Social Security during the General Enrollment Period. His cover starts February 1. He pays the standard premium of $202.90 per month (Ledger A1). Medicare reviews his two years without Part B and adds a late penalty to his premium, which he will pay as long as he has Part B. Sam is not glad about the penalty. But his February care is now covered under Part B rules, after the $283 deductible (Ledger A2). His one regret is time: if he had applied in his first window, there would be no penalty and no gap.

Mark the window on your calendar

If you missed your first Part B window, the year is not lost. January 1 opens the route back. Apply early in the window, and your cover starts the month after you sign up. If a Medicare Savings Program might pay your premium, start that state process in the same weeks, so the two lines meet. Our Paying for Care section holds the guides that sit next to this one, on penalties, savings programs, and plan choices.

Sources

• https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-does-medicare-coverage-start