First enrollment

Turning 65: what the seven-month window asks of you

The Initial Enrollment Period spans three months before your birth month, the month itself, and three months after. What you file inside that stretch determines whether coverage begins on time and whether a permanent surcharge follows you.

Figures reviewed for 2026

7 months
Length of the first window: 3 months
Lead time before the birth month: 6 months
Supplement protection once Part B starts: $283
Part B deductible for 2026

Your birth month sets the clock

The window hangs on the month, not the day. Turning 65 in September means the door opens June 1 and closes March 31. Filing early is not merely tidy paperwork; it decides whether coverage starts on the first of your birth month or slips several weeks later and leaves a hole.

There is one calendar quirk: people born on the first day of a month are treated as reaching 65 the month before. Their window shifts a month earlier, so confirm the exact dates with Social Security instead of assuming.

When the coverage actually switches on

File in the three months before your birth month and benefits begin on day one of that month. File during the birth month and they begin the first of the next. Each month you wait after that pushes the start date further out, reaching three months after filing if you use the final month of the window.

Filing date versus start date

You file	Benefits begin
1 to 3 months before the birth month	First day of the birth month
During the birth month	First day of the next month
One month after the birth month	Two months after filing
Two or three months after the birth month	Three months after filing

Automatic filing versus doing it yourself

Already receiving Social Security retirement or Railroad Retirement Board payments? Parts A and B arrive without action, the card shows up about three months before the birthday, and the Part B charge is withheld from the monthly check.

Not drawing benefits, or deliberately postponing them? The filing is on you, through ssa.gov, a phone call, or a local office visit. Filing for Part A alone is also permitted, which lets an employer plan stay primary; people still working choose it often.

The four decisions waiting inside the window

Part A is usually automatic and free, so it is barely a decision. Part B is the first real one: $202.90 a month in 2026, worth postponing only when current-employer coverage is creditable. Part D is the second, and going without creditable drug coverage creates a surcharge that never expires.

The third is the assembly: government Medicare with a supplement plus a drug plan, or an Advantage plan. The fourth is sequencing. If a supplement is in your future, the six-month protection begins the month Part B does, and it does not return.

Guard the supplement window above all

For six months after Part B begins, and only at 65 or older, an insurer must sell you any Medigap policy it offers in your state, without health questions and without a condition-based surcharge. Afterwards most states allow underwriting, and a diagnosis can mean a decline or a rate you would not choose.

Hence the order of operations: file Part B on schedule, open the supplement application in the same stretch, and do not let a short-term health problem close the door on the policy you actually want.

Where new enrollees tend to stumble

Every item on that list is easy to avoid with a little warning and expensive to discover afterwards. It is why we ask about employer size, prescriptions and physicians before we ever discuss price.

Treating a Marketplace plan as a substitute for Medicare. It is not, and eligibility for Medicare can end your subsidy.
Postponing Part B while COBRA runs. COBRA does not count as creditable coverage and will not shield you from a surcharge.
Skipping drug coverage because the pharmacy bill is zero today. The penalty arrives later and stays.
Waiting past the supplement window, sometimes by only a few weeks and one diagnosis.
Forgetting to close out the old plan so the two sets of dates line up.

Official source

The federal guide behind this page

Medicare publishes its own handbook on this topic. It is linked here so you can check any figure on this page against the source.

Medicare: Getting StartedCMS 11389Read the PDF Order print

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First enrollment

Questions people ask about this

If I am still employed at 65, do I have to do anything?

Sometimes. A small employer, under 20 employees, requires you to enroll because Medicare pays first. At a larger employer you may postpone Part B while that coverage remains active and file later without a surcharge. Free Part A is often still worth taking, unless a health savings account is in play.

What happens if the window closes without a filing?

January 1 through March 31 becomes your annual opportunity through the General Enrollment Period, with benefits starting the month after you sign up. A Part B surcharge of 10 percent per twelve months of delay generally follows you from then on.

My birthday falls on the first. Anything different?

Possibly, because the eligibility month can move a month earlier and take your window with it. Verify the dates with Social Security before building a plan around them.

Can I file for Part B after 65 with no penalty?

Yes, if you had creditable coverage through current employment. You get eight months measured from the end of that employment or that coverage. Retiree plans, COBRA and most individual policies do not qualify.

Should I take Part A if I am not retiring?

For most people yes, because it costs nothing and can act as secondary coverage behind a group plan. The clear exception is an HSA: enrolling in any part of Medicare ends your ability to keep contributing.

Official sources

Check it at the source

Every figure on this page comes from the agencies below. They are the primary record, and none of these links costs you anything.

Keep reading

Medicare enrollment periodsEvery window in one place Working past 65How employer size changes the answer Getting started checklistThe steps in working order Medigap Plan GThe most common choice after Part B starts

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