Seven months, and the timing inside it matters
Your Initial Enrollment Period runs for seven months: the three months before your birthday month, the month itself, and the three months after. Signing up in the first three generally means coverage starts sooner, which is why the advice is to act early in the window rather than in it.
If you are already receiving Social Security benefits you are usually enrolled in Parts A and B automatically and your card arrives without you doing anything. If you are not, nothing happens until you act.
Do you actually need Part B yet?
This is the one real decision at 65, and it turns on your current coverage. If you have coverage from current employment, whether you can safely delay Part B depends on the size of the employer.
If the employer has 20 or more employees, the group plan generally pays first and delaying Part B is usually safe. If it has fewer than 20, Medicare generally pays first, and not taking Part B can leave you with very large uncovered bills. Getting this backwards is expensive, so confirm with the employer benefits administrator rather than assuming.
Your Medigap clock starts with Part B
The month you are 65 or over and enrolled in Part B, a six-month Medigap open enrollment period starts. During it any insurer must sell you any Medigap policy it offers, at the healthy rate, with no health questions.
It does not come back. If you take a Medicare Advantage plan at 65 and want Medigap at 70, you will generally face medical underwriting in Florida and can be declined. Whichever you choose, choose it knowing that.
What to do, in order
Working backwards from your birthday month, this is the sequence that avoids the common mistakes.
- Three months before: confirm whether your current coverage lets you delay Part B, in writing, from your benefits administrator.
- Three months before: write down your prescriptions with dose and frequency, and your doctors with their practice names.
- Three months before: sign up for Part A, and Part B unless you have confirmed a reason to delay.
- Birthday month: compare Medicare Advantage against Original Medicare with Medigap and a Part D plan, on annual total cost rather than premium.
- Birthday month: if you choose Medigap, apply inside the six-month window.
- After enrolling: check that your doctors and drugs are covered before the plan starts, not after.
Frequently asked questions
Am I enrolled in Medicare automatically at 65?
Only if you are already receiving Social Security or Railroad Retirement benefits, in which case Parts A and B usually start automatically. If you are not receiving benefits yet, you must sign up yourself during your Initial Enrollment Period.
Should I take Part B if I am still working at 65?
It depends on the size of your employer. With 20 or more employees the group plan generally pays first and delaying is usually safe. With fewer than 20, Medicare generally pays first and delaying can leave you with large uncovered bills.
When does my Medigap open enrollment start?
The first month you are both 65 or older and enrolled in Part B. It lasts six months, during which no insurer can refuse you or charge you more for health reasons, and it does not reopen afterwards.
What if I miss my Initial Enrollment Period?
If you have no Special Enrollment Period, you would generally wait for the General Enrollment Period from 1 January to 31 March, and you may owe a Part B late enrollment penalty for as long as you have Part B.
Sources
This guide explains officially published rules and figures. It is not an insurance quote and not an eligibility determination. Only HealthCare.gov, Medicare.gov, Social Security or the carrier can determine your eligibility and your actual price.
We do not offer every plan available in your area. Any information we provide is limited to those plans we do offer. Please contact Medicare.gov or 1-800-MEDICARE to get information on all of your options. Not connected with or endorsed by the U.S. government or the federal Medicare program.
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