Turning 65: How to Sign Up for Medicare

Published by MedicareQuotesForYou. Published July 29, 2026. Last reviewed July 29, 2026.

Short answer

Your Initial Enrollment Period lasts seven months: the three months before the month you turn 65, your birthday month, and the three months after. Signing up in the three months before your birthday month generally means coverage starts on the first day of your birthday month.

If you already receive Social Security or Railroad Retirement benefits, you are enrolled in Part A and Part B automatically and your card arrives in the post. If you are not receiving those benefits, nobody enrolls you — you have to do it yourself through the Social Security Administration, online at ssa.gov, by phone, or at a local office.

The main exception is if you are still working and covered by a qualifying employer group health plan. In that case you may be able to delay Part B without penalty and enroll later through a Special Enrollment Period. Whether that applies depends on the size of the employer, and getting it wrong is expensive.

Your seven-month window

When you enroll determines when coverage begins. Example shown for someone whose 65th birthday is in June.
When you sign up	Example months	When coverage starts
3 months before your birthday month	March, April, May	First day of your birthday month (June 1)
Your birthday month	June	First day of the following month
1 to 3 months after your birthday month	July, August, September	First day of the month after you sign up
After the window closes	October onward	You generally wait for the General Enrollment Period (January 1 to March 31), and a late enrollment penalty may apply

If your birthday falls on the first of the month, your window shifts one month earlier. It is worth confirming your exact dates rather than assuming.

Step by step

Around three months before you turn 65, check whether you will be enrolled automatically. If you are already drawing Social Security or Railroad Retirement benefits, you will be. If not, you need to act.
Decide whether you need Part B now. If you have no other coverage, yes. If you are still working with employer coverage, read the section below before deciding.
Enroll in Part A and Part B through the Social Security Administration — online at ssa.gov, by phone on 1-800-772-1213, or at a local office. Medicare enrollment is handled by Social Security, not by Medicare itself.
Choose how you want your coverage delivered. Either Original Medicare, usually with a Medigap policy and a separate Part D drug plan, or a Medicare Advantage plan that bundles it together. See Advantage vs Original Medicare and Advantage vs Medigap.
If you want Medigap, act inside your six-month Medigap open enrollment window. It normally begins when you are 65 or older and enrolled in Part B. This is when you can buy any policy sold in your state regardless of your health.
Sort out drug coverage. Either a standalone Part D plan alongside Original Medicare, or a Medicare Advantage plan that includes it. Skipping this creates a penalty that never goes away.

If you are still working at 65

This is where most expensive mistakes happen, and the answer turns on how many people your employer has.

Employer with 20 or more employees. The group plan generally pays first and Medicare second. Many people in this position delay Part B without penalty and enroll later through a Special Enrollment Period when the employment or the coverage ends.
Employer with fewer than 20 employees. Medicare generally pays first. If you do not enroll, your employer plan may pay very little, leaving you exposed even though you believe you are covered. Confirm with the plan administrator in writing.

Three traps that catch people out

COBRA and retiree coverage do not count as active employer coverage. Neither one gives you the Special Enrollment Period that active employment does. People who take COBRA at 65 and delay Part B often discover the penalty and the coverage gap much later.

Health Savings Accounts and Medicare do not mix. Once you enroll in any part of Medicare you can no longer contribute to an HSA. Because Part A can be backdated by up to six months when you enroll after 65, people who contribute right up to their enrollment date can end up with contributions that were not permitted. If you have an HSA, stop contributing well before you enroll and confirm the timing.

Marketplace and ACA plans are not employer coverage. Having a Marketplace plan does not let you delay Part B without penalty, and subsidies generally end when you become eligible for Medicare.

What it costs, in structure

We do not quote dollar figures for a plan year until the Centers for Medicare & Medicaid Services has published them, which happens in the autumn each year. What does not change is the structure of what you pay:

Part A is premium-free for most people, based on your own or a spouse's work history. If you do not have enough work credits, there is a premium.
Part B has a standard monthly premium. Higher earners pay an income-related surcharge, based on a tax return from two years earlier.
Part D has its own premium, and higher earners pay a surcharge here too.
Medigap has a premium that varies by plan letter, insurer, state and age.
Medicare Advantage often has a $0 plan premium, but you still pay the Part B premium plus copays when you use care.

If the income-related surcharge is based on a year when you earned much more than you do now — because you have since retired, for example — you can ask Social Security to reconsider it based on your current circumstances.

The penalties, and why they matter

Part B: if you were not covered by qualifying employer insurance and did not sign up when first eligible, your premium can rise by 10% for each full 12-month period you could have had Part B but did not. In most cases it lasts as long as you have Part B.

Part D: going 63 days or more without Part D or other creditable drug coverage after your Initial Enrollment Period adds a permanent amount to your Part D premium, calculated from how many months you went without.

Both are avoidable and neither is easy to remove afterwards. If you are approaching 65 with employer coverage, ask your plan administrator for written confirmation that it counts as creditable — before your birthday, 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 when you turn 65. In that case Part A and Part B start automatically and your card arrives in the post. If you are not receiving those benefits, no one enrolls you and you must sign up yourself through the Social Security Administration.

Do I have to enroll in Medicare if I am still working?

It depends on the size of your employer. With 20 or more employees, the group plan generally pays first and many people delay Part B without penalty, enrolling later through a Special Enrollment Period. With fewer than 20 employees, Medicare generally pays first and delaying can leave you badly underinsured. Confirm with your plan administrator in writing.

When should I apply so my coverage starts on my 65th birthday month?

Apply during the three months before your birthday month. Coverage then generally begins on the first day of your birthday month. Applying later delays the start date.

Where do I actually sign up for Medicare?

Through the Social Security Administration, not Medicare. You can apply online at ssa.gov, by phone on 1-800-772-1213, or at a local Social Security office.

Can I keep contributing to my HSA after I turn 65?

Only if you have not enrolled in any part of Medicare. Once you enroll, contributions must stop. Because Part A can be backdated up to six months when you enroll after 65, it is important to stop contributing in advance and confirm the exact timing rather than assume.

Does COBRA count as employer coverage for delaying Part B?

No. COBRA and retiree coverage do not give you the Special Enrollment Period that active employment-based coverage does. Relying on COBRA to delay Part B commonly results in a late enrollment penalty and a gap in coverage.

Turning 65 soon? Talk it through with a licensed agent

Tell us a little about your situation and a licensed insurance agent can confirm your dates, whether you can delay Part B, and what is available where you live. There is no cost and no obligation.

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Medicare Advantage vs Original Medicare — the first choice you will make
Medicare Advantage vs Medigap — if you are leaning towards Original Medicare
Medicare enrollment periods and deadlines — every window explained