The seven-month window
The Initial Enrollment Period runs for 7 months: the three months before the month of the 65th birthday, the birthday month itself, and the three months after it.
When coverage starts depends on which month within the window the sign-up happens, and coverage always begins on the first of a month. Signing up in the three months before the birthday is what gets coverage starting without a gap.
People already receiving Social Security are usually enrolled automatically. Everyone else has to act, and nothing arrives in the post to tell them the window has opened.
Work out the seven months
The rule is above and it is short. The reason people still miss the window is that it is measured from the month of the 65th birthday rather than from the birthday, so the arithmetic is easy to do wrong in either direction. Put in the month and year of birth and the seven months are named.
- The three months before the month they turn 65Signing up in these three is what gets coverage starting without a gap.
- The month they turn 65
- The three months after that monthStill inside the window. Coverage starts later, and how much later depends on the month.
This counts whole months, because that is how the rule is written. It does not ask for a day of birth, and two things follow from that: it is less of your family's information to hand a web page, and it cannot tell you about the separate treatment Medicare gives a birthday that falls on the first of a month. If the birthday is the first, check that point with Medicare before relying on these months.
This works out the months in your browser. Nothing you type here is sent to Sahvelo, saved, or kept when you close the page.
This is the Initial Enrollment Period and nothing else. Someone covered by an employer group health plan through current work has a different window, and leaving that job starts its clock; Sahvelo has not verified its length at source and does not state one.
Why missing it is permanent
This is about the Initial Enrollment Period, and the consequence Medicare attaches to missing it is Part B’s: waiting to sign up, and then a monthly late-enrollment penalty for as long as that Part B coverage lasts. The penalty grows the longer the delay. A Part A premium can attract one too, where Part A is not premium-free — which is a minority of people. Somebody who qualifies for a Special Enrollment Period instead is not in this position at all; the next section is theirs.
This is not a one-off fee. Medicare describes it as charged for as long as the coverage lasts, which is what makes a few months of inattention expensive for a very long time.
Source 2The exception for people still working
Somebody covered by a group health plan based on their own or a spouse’s current employment may be able to delay Part B without a late-enrollment penalty and enroll later through a Special Enrollment Period. Medicare sets the conditions, including rules that turn on the size of the employer.
Two things about that exception catch people. It depends on coverage from current employment, so retiree coverage and COBRA generally do not qualify. And the special window after that coverage ends is time-limited, so leaving a job starts a clock.
Sahvelo has not verified the length of the special window or the precise employer-size rules to Tier 1, and does not state them. Medicare publishes both, and the link is below.
What enrolling does not buy
Families arrive at Medicare enrollment expecting it to be the answer to how a parent will be looked after. It is not, and Medicare says so plainly: long-term care — the day-to-day help with bathing, dressing, eating and moving — is not covered.
What is covered is medical, and it is worth claiming: a hospital stay, a limited period of rehabilitation after one, home health under specific conditions, and hospice. Those have their own rules, their own clocks and their own appeal rights, and they are where a caregiver's harder questions usually lead.
- Rehab and skilled nursing — what Medicare pays for after a hospital stay, and for how long
- Leaving hospital — the discharge appeal, and why an observation stay is not an admission
- Home health and home care — the four conditions, and the one families fail
- Medicaid and long-term care — the route that does pay for it, and what it costs the estate
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Sahvelo gives information drawn from statutes, agency guidance and official forms. It is not legal advice for your particular situation. Terms & disclaimer.
Questions people ask about this
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Will they be signed up automatically?
Usually only if they are already receiving Social Security benefits when they turn 65. Someone who has delayed claiming Social Security — increasingly common — is not enrolled automatically and has to act inside the window. -
What are the parts?
Part A covers hospital care and is premium-free for most people with sufficient work history. Part B covers outpatient care and has a monthly premium. Part D covers prescriptions. Medicare Advantage, sometimes called Part C, is a private alternative that bundles them. The Initial Enrollment Period deadline this page is about is Part B’s. -
They have COBRA. Does that count as employer coverage?
Generally no for this purpose, and it is a costly misunderstanding. Relying on COBRA past 65 can produce both a coverage gap and a Part B late-enrollment penalty. Confirm with Medicare directly before delaying on the strength of COBRA. -
A parent is moving in with us from another state. Does Medicare move?
Original Medicare travels nationally. A Medicare Advantage or Part D plan is tied to a service area and generally does not, so a move usually creates a special enrollment right and a decision to make. That is worth checking before the move rather than after.
Related from the Sahvelo Journal: Medicare vs. Medicaid for a Parent's Long-Term Care (opens in a new tab)
Official links you'll need
Every link goes directly to the issuing agency or the official tool, and opens in a new tab.
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Check Medicare's sign-up windows (opens in a new tab)
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Apply for Medicare through Social Security (opens in a new tab)
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Find free local Medicare counseling (SHIP) (opens in a new tab)
Federally funded, free, and not selling anything — which is unusual in this market.
Where this sits in the process
Related
- Essential documentsthe Medicare card belongs with the rest of the file
- HIPAA authorizationhelping with claims usually needs written authority
- Social Securitythe same agency handles Medicare enrollment
Sources
Medicare is federal, and CMS publishes the enrollment rules directly.
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Medicare.gov — When does Medicare coverage start (opens in a new tab)
The seven-month Initial Enrollment Period and when coverage starts.
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Medicare.gov — late enrollment penalty (opens in a new tab)
The late-enrollment penalty and that it lasts as long as coverage does.
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Medicare.gov — Long-term care coverage (opens in a new tab)
That Medicare does not pay for long-term care, in Medicare's own words.
Sources last reviewed 2026-08-12. Where a source is marked pending re-verification, the page says so wherever the claim appears.