When You Can Start Medicare Coverage

The Age Rule and Other Paths to Medicare

You become may be able to access for Medicare at age 65, regardless of your work history or income. If you were born on the 1st of the month, Medicare starts the month before you turn 65. If you were born on any other day, it starts the month you turn 65. You do not have to retire to get Medicare — you can keep working and carry both your employer coverage and Medicare at the same time.

You can also become may be able to access before 65 if you have been receiving Social Security Disability Insurance (SSDI) for 24 months, or if you have end-stage renal disease (ESRD) or amyotrophic lateral sclerosis (ALS). These conditions bypass the age requirement entirely.

Key Takeaways

Medicare starts automatically at 65 if you are already collecting Social Security; otherwise you must sign up during your enrollment window.
You can get Medicare before 65 if you have been on SSDI for 24 months, have ESRD, or have been diagnosed with ALS.
Missing your enrollment window results in a permanent monthly penalty added to your Part B and Part D premiums for as long as you have Medicare.
If you are still working at 65 and have employer coverage, you may be able to delay Part B without penalty if your employer has 20 or more employees.

Enrollment Windows and When to Sign Up

Your Initial Enrollment Period is a seven-month window: three months before the month you turn 65, the month you turn 65, and three months after. You can sign up online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

If you miss this window, you enter the General Enrollment Period, which runs January 1 through March 31 each year. Coverage under General Enrollment does not start until July 1 of that year, creating a gap. More importantly, you will owe a permanent penalty: 10 percent more per month for every 12 months you were late signing up for Part B, and 1 percent per month for Part D. These penalties stay with you for life.

The one exception is the Special Enrollment Period. If you are still working at 65 and your employer has 20 or more employees, you can delay Part B without penalty as long as you are covered by the employer plan. You have eight months after you leave that job or lose the coverage to sign up for Part B without penalty.

Working Past 65 and Employer Coverage

Turning 65 does not mean you must stop working or drop your employer health plan. If your employer has 20 or more employees, your employer coverage is the primary payer, and Medicare is secondary. You can stay on the employer plan and delay Medicare Part B without incurring a late-enrollment penalty.

However, you should still sign up for Part A (hospital insurance) at 65, even if you are working, because Part A is usually free and has no penalty for late enrollment. Part B (medical insurance) is where the penalty applies if you delay without may have access to for the exception.

Once you leave the job or the employer coverage ends, you have a Special Enrollment Period of eight months to sign up for Part B. After that window closes, the standard late-enrollment penalty applies.

Medicare Before 65: SSDI, ESRD, and ALS

If you have been receiving SSDI for 24 consecutive months, you become may be able to access for Medicare automatically. The 24-month clock starts from the month your SSDI benefits began, not from when you applied. You do not need to sign up separately — Medicare Part A and Part B coverage begins automatically in the 25th month of your SSDI may be able to access.

If you have end-stage renal disease (ESRD) — permanent kidney failure requiring dialysis or transplant — you become may be able to access for Medicare regardless of age. Coverage can begin as early as the first day of the month in which you start dialysis, or the month before a scheduled kidney transplant. You must sign up; it does not happen automatically.

If you are diagnosed with ALS (amyotrophic lateral sclerosis), you become may be able to access for Medicare when ready, without waiting for SSDI approval or any other condition. You should sign up as soon as you receive your diagnosis.

What Happens If You Miss Your Enrollment Window

Missing your Initial Enrollment Period does not prevent you from getting Medicare — it only delays coverage and adds a permanent cost. Under the General Enrollment Period, you can sign up January through March, but coverage does not start until July 1. This creates a five-month gap with no Medicare coverage.

The financial penalty is steeper than most people expect. For Part B, you pay 10 percent more per month for every 12 months you were late. If you were three years late, you pay 30 percent more every month for the rest of your life. For Part D (prescription drug coverage), the penalty is 1 percent per month of delay, compounded annually. These penalties do not expire.

The only way to avoid the penalty is to show you had creditable coverage — employer coverage, TRICARE, or another plan that covers at least as much as Medicare Part B — during the months you were late. You will need documentation from that plan to prove it.

Turning 65 While Still on Employer Coverage

If you turn 65 while employed and your employer has 20 or more employees, you have options. You can stay on the employer plan as your primary coverage and delay Medicare Part B. Your employer plan will remain primary, and Medicare will not pay anything until the employer plan has paid first.

You must still enroll in Part A at 65 — it is usually free and has no late-enrollment penalty. For Part B, you have until eight months after you leave the job or lose coverage to sign up without penalty. After that, the standard 10 percent monthly penalty applies for every 12 months you were late.

If your employer has fewer than 20 employees, Medicare becomes primary at 65, and you should sign up for both Part A and Part B during your Initial Enrollment Period to avoid penalties.

Frequently Asked Questions

What if I turn 65 but do not want Medicare yet?

If you are still working and have employer coverage through an employer with 20 or more employees, you can delay Part B without penalty. You must still sign up for Part A. If your employer has fewer than 20 employees, Medicare becomes primary at 65, and you should enroll to avoid penalties.

Do I automatically get Medicare when I turn 65?

Only if you are already receiving Social Security benefits. If you have not claimed Social Security yet, you must sign up for Medicare separately during your Initial Enrollment Period (three months before through three months after you turn 65) to avoid a permanent penalty.

Can I get Medicare before 65 without SSDI?

Yes, if you have end-stage renal disease or ALS. Both conditions make you may be able to access for Medicare when ready, regardless of age. You must sign up; coverage does not start automatically.

What is the penalty for signing up late?

For Part B, you pay 10 percent more per month for every 12 months you were late. For Part D, the penalty is 1 percent per month. These penalties are permanent and do not go away. The only exception is if you had creditable coverage during the months you were late.

How do I sign up for Medicare?

You can sign up online at Medicare.gov, call 1-800-MEDICARE, or visit your local Social Security office in person. Your Initial Enrollment Period is seven months long: three months before you turn 65, the month you turn 65, and three months after.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.