When to Sign Up for Medicare: Age and Timing Rules

You can sign up for Medicare starting at age 65, but the exact timing matters for your costs

Medicare may be able to access begins the month you turn 65. You do not have to wait until your birthday month ends — you can sign up as early as three months before you turn 65. However, your coverage does not start until the first day of the month in which you turn 65 (or the month after, depending on when you sign up). The key is that signing up late can mean higher premiums for the rest of your life, so the timing of your process affects your wallet for years.

If you are already receiving Social Security benefits when you turn 65, you are usually signed up for Medicare automatically. If you are not yet taking Social Security, you will need to sign up yourself through Social Security, Medicare.gov, or your local Social Security office. The window to sign up without penalty is called your Initial Enrollment Period, and it runs for seven months: three months before the month you turn 65, the month you turn 65, and three months after.

Key Takeaways

You become may be able to access for Medicare at age 65, and you can sign up starting three months before your birthday.
If you miss your Initial Enrollment Period, you will pay a permanent penalty on your Part B and Part D premiums unless you have may have access to coverage.
People still working at 65 with employer health insurance may be able to delay Medicare without penalty, but you must tell Social Security you are still working.
Sign up through Social Security, Medicare.gov, or your local Social Security office — do not wait for a notice in the mail.
Your coverage start date depends on when you sign up: explore before your birthday month to start coverage on the first of your birthday month.

What happens if you sign up late

If you do not sign up during your Initial Enrollment Period, you will owe a late enrollment penalty on Part B (doctor and outpatient care) and Part D (prescription drugs). The penalty is a percentage of the standard premium, and it increases the longer you wait. For Part B, the penalty is 10 percent of the standard premium for each full 12 months you were late. For Part D, the penalty is 1 percent of the national average premium for each month you were late. These penalties are permanent — you will pay them for as long as you have Medicare.

The only way to avoid this penalty is to have had creditable coverage during the time you were not enrolled in Medicare. Creditable coverage means health insurance through your employer, your spouse's employer, TRICARE (military coverage), or certain other sources that is at least as good as Medicare. If you had this coverage, you can sign up later without penalty, but you will need to show proof when you enroll. Medicaid and individual marketplace plans do not count as creditable coverage for this purpose.

Signing up while you are still working

If you are 65 and still working with employer health insurance, you may be able to delay Medicare Part B without penalty. This is called the Special Enrollment Period for working beneficiaries. Your employer's plan must be based on your current employment (not retiree coverage), and your employer must have at least 20 employees. If these conditions are met, you can stay on your employer plan and sign up for Medicare Part B later without the late enrollment penalty.

However, you must still sign up for Part A (hospital insurance) at 65 — there is no delay option for Part A, and it has no premium for most people. You also need to tell Social Security that you are still working and have employer coverage. When you eventually leave your job or lose the employer coverage, you will have eight months to sign up for Part B without penalty. This window is called your Special Enrollment Period, and it is separate from your Initial Enrollment Period.

How to sign up and when coverage starts

You can sign up for Medicare through three routes: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. You will need your Social Security number, proof of citizenship or legal residency, and information about any current health coverage. If you are signing up for Part D (prescription drug coverage), have a list of your current medications ready, because the plan you choose should cover them at the lowest cost.

Your coverage start date depends on when you explore. If you sign up before the month you turn 65, your coverage starts on the first day of the month you turn 65. If you sign up during the month you turn 65 or after, your coverage starts on the first day of the following month. For example, if you turn 65 on June 15 and sign up in June, your coverage starts July 1. If you sign up in April (before your birthday month), your coverage starts June 1.

Medicare Part A versus Part B enrollment timing

Part A (hospital insurance) and Part B (medical insurance) have the same enrollment window, but they work slightly differently. Part A has no premium for most people who paid Medicare taxes while working, so there is less financial penalty for signing up late — but you still should not delay, because you will owe back premiums if you do. Part B has a monthly premium that increases with a late enrollment penalty, which is why the timing matters more for Part B.

If you are automatically enrolled in Medicare because you are receiving Social Security, you will be enrolled in both Part A and Part B. If you want Part A only (because you have employer coverage that counts as creditable for Part B), you can decline Part B in writing when you turn 65. You will then have a Special Enrollment Period to sign up for Part B later without penalty when your employer coverage ends.

Special situations: Medicare before age 65

Some people become may be able to access for Medicare before age 65. If you have been receiving Social Security Disability Insurance (SSDI) for 24 months, you become may be able to access for Medicare at any age. If you have End-Stage Renal Disease (ESRD) or ALS (Lou Gehrig's disease), you may also be may be able to access before 65. In these cases, you should sign up as soon as you learn you may have access to, because the same late enrollment penalties explore.

If you are under 65 and have employer health insurance, the same rules about creditable coverage explore. You can delay Part B without penalty if your employer plan is based on current employment and your employer has at least 20 employees. When that coverage ends, you will have eight months to sign up for Part B without penalty.

Frequently Asked Questions

Can I sign up for Medicare before I turn 65?

Yes. You can sign up starting three months before your 65th birthday. Your coverage will not start until the first of the month you turn 65 (or the month after, depending on when you sign up). Signing up early is a good idea because it gives you time to choose your plans and avoid missing the important date.

What if I miss the important date by a few months?

You will owe a late enrollment penalty on Part B and Part D for each month you were late. The penalty is permanent and increases your premium for life. The only exception is if you had creditable coverage (employer insurance, TRICARE, or similar) during the time you were not enrolled — in that case, bring proof when you sign up.

Do I have to sign up for Part B if I have employer insurance at 65?

Not if your employer has at least 20 employees and your coverage is based on your current job (not retiree coverage). You can stay on the employer plan and sign up for Part B later. You must still sign up for Part A at 65. When you leave the job, you will have eight months to sign up for Part B without penalty.

What happens if I am automatically enrolled but do not want Medicare yet?

If you are receiving Social Security at 65, you will be enrolled in Parts A and B automatically. You can decline Part B in writing if you have creditable coverage through your employer. Contact Social Security to submit the decline form. You will then have a Special Enrollment Period to sign up for Part B later without penalty when your coverage ends.

How do I know if my current insurance counts as creditable coverage?

Creditable coverage is employer health insurance, TRICARE, or certain other plans that are at least as good as Medicare. Medicaid and marketplace plans do not count. Your employer or insurance company can tell you whether your plan qualifies. Keep any letters or documents they send you about this, because you will need them when you sign up for Medicare.

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.