When You Can Start Using Medicare: Age, Work History, and Timing

You can start using Medicare at 65, or earlier if you have a disability or end-stage renal disease

Most people become may be able to access for Medicare when they turn 65, regardless of whether they are still working. If you have a disability, you may be may be able to access as early as age 18 — but you must have worked and paid Medicare taxes for a certain length of time. If you have end-stage renal disease (permanent kidney failure requiring dialysis or transplant), you can start Medicare at any age, though again, work history matters for some parts of the program.

The key is understanding which part of Medicare you can use and when. Medicare has four parts — A, B, C, and D — and the timing rules differ for each one. Part A (hospital insurance) is usually free at 65 if you have worked long enough. Part B (doctor visits and outpatient care) requires a monthly premium and you must sign up during a specific window or face a penalty. Part C (Medicare Advantage) and Part D (prescription drug coverage) are optional add-ons with their own enrollment periods.

Key Takeaways

You become may be able to access for Medicare at age 65 if you have worked and paid Medicare taxes for at least 10 years (40 quarters).
You can start Medicare earlier if you have been receiving Social Security disability benefits for 24 months, or if you have end-stage renal disease.
Part A (hospital insurance) is usually automatic and free at 65, but Part B requires you to sign up during your initial enrollment period or pay a permanent penalty.
Your initial enrollment period is the three months before, the month of, and the three months after your 65th birthday — a seven-month window to sign up without penalty.
If you are still working at 65 and have health insurance through your job, you may be able to delay Part B enrollment without penalty if your employer has 20 or more employees.

may be able to access at age 65: work history and citizenship

To start Medicare at 65, you must be a U.S. citizen or permanent resident who has lived in the United States for at least five consecutive years. You also need to have worked and paid Medicare taxes for at least 10 years — this is measured in quarters, so 40 quarters total. A quarter is roughly three months, and you can earn up to four quarters per year. If you worked for 10 years at any point in your life, even if it was decades ago, you likely have enough quarters.

Your spouse may also be may be able to access at 65 based on your work history alone, even if they never worked or did not work long enough. This is called spousal coverage. You do not need to be receiving your own Social Security benefits yet to sign up for Medicare — you can start Medicare at 65 and delay your Social Security benefits until later if you choose.

Starting Medicare before 65: disability and kidney disease

If you have been receiving Social Security Disability Insurance (SSDI) for 24 months, you become may be able to access for Medicare regardless of your age. This means if you are approved for disability at age 40, you will become may be able to access for Medicare at age 42. The 24-month waiting period starts from the month you are approved for disability, not from the month you applied.

If you have end-stage renal disease, you can start Medicare when ready, even if you are younger than 65 and have not been on disability. You will need documentation from your doctor or dialysis center confirming the diagnosis. Some people with end-stage renal disease also may have access to for SSDI, which would make them may be able to access even sooner in some cases, but the kidney disease itself is enough.

If you have ALS (amyotrophic lateral sclerosis), you do not have to wait 24 months for SSDI — you become may be able to access for Medicare as soon as you are approved for disability benefits, which can happen much faster.

Your initial enrollment period and why it matters

Your initial enrollment period is a seven-month window: the three months before you turn 65, the month you turn 65, and the three months after. During this time, you can sign up for Medicare Part A and Part B without any penalty. If you miss this window, you will owe a permanent penalty on your Part B premium for as long as you have Medicare.

The Part B penalty is 10 percent of the standard premium for each 12-month period you were may be able to access but did not sign up. If you delay signing up for three years, your premium will be 30 percent higher than the standard amount, and that increase stays with you for life. Part A does not usually have a penalty, but it is still important to sign up during your initial enrollment period to avoid confusion and gaps in coverage.

You can sign up for Medicare through Social Security (online at ssa.gov, by phone at 1-800-772-1213, or in person at your local Social Security office), through Medicare.gov, or by calling 1-800-MEDICARE. If you are already receiving Social Security benefits, you will be enrolled in Part A and Part B automatically three months before you turn 65 — you do not have to do anything unless you want to decline Part B.

Still working at 65: when you can delay Part B

If you are still working at 65 and have health insurance through your job, you may not need to sign up for Medicare Part B right away. If your employer has 20 or more employees, you can delay Part B without penalty as long as you are covered by the employer plan. This is called the working exception. Once you stop working or lose your employer coverage, you have eight months to sign up for Part B without penalty.

Part A is different — you should still sign up for Part A at 65 even if you are working, because it is usually free and covers hospital stays. Delaying Part A does not carry a penalty, but there is no advantage to waiting.

If your employer has fewer than 20 employees, you should sign up for Part B at 65 even if you are working, because the working exception does not explore. Check with your employer's human resources department if you are unsure of the company size.

Coordinating Medicare with other coverage

If you have coverage through a spouse's employer plan, COBRA, a union plan, or Veterans benefits, the rules for delaying Medicare can be different. Some types of coverage allow you to delay without penalty; others do not. It is worth checking with the plan administrator before you turn 65 to understand whether you need to sign up right away.

If you are on Medicaid (the state program for low-income people), you can have both Medicaid and Medicare at the same time. Medicaid will help pay your Medicare premiums and cover costs that Medicare does not. You do not lose Medicaid when you turn 65 and start Medicare — the two programs work together.

Part C and Part D enrollment: different timelines

Part C (Medicare Advantage) and Part D (prescription drug coverage) have their own enrollment periods separate from your initial enrollment period for Part A and B. You can sign up for Part C and Part D during your initial enrollment period, but you can also join during the annual open enrollment period (October 15 to December 7 each year) or if you have a may have access to life event like losing employer coverage.

If you do not sign up for Part D when you first become may be able to access, you will owe a penalty on your premiums for each month you were without coverage — similar to the Part B penalty. The penalty is about 1 percent of the national average Part D premium for each month of delay. If you go 63 days or more without Part D coverage, the penalty applies.

Frequently Asked Questions

What happens if I turn 65 and do not sign up for Medicare?

If you do not sign up for Part B during your initial enrollment period, you will owe a permanent 10 percent penalty on your premium for each 12-month period you delayed. Part A usually does not have a penalty, but you should still sign up to avoid gaps in coverage. The penalty applies for the rest of your life, so it is important to enroll on time.

Can I start Medicare before I start Social Security?

Yes. You can sign up for Medicare at 65 and delay your Social Security benefits until age 70 if you want. Medicare and Social Security are separate programs. However, if you are already receiving Social Security, you will be automatically enrolled in Medicare at 65.

Do I have to sign up for Part B if I have employer coverage?

Not if your employer has 20 or more employees and you are actively working. You can delay Part B without penalty as long as you have employer coverage. Once you leave the job or lose coverage, you have eight months to sign up. If your employer has fewer than 20 employees, you should sign up for Part B at 65.

What if I am disabled but under 65?

If you receive SSDI, you become may be able to access for Medicare after 24 months of benefits. If you have end-stage renal disease or ALS, you may be may be able to access sooner. Contact Social Security or Medicare to confirm your may be able to access date and to sign up.

Can I change my mind after I sign up for Medicare?

Yes, but only during certain windows. You have a seven-month initial enrollment period, and you can make changes during the annual open enrollment period (October 15 to December 7). If you made a mistake during your initial enrollment period, you may be able to request a special enrollment period — contact Medicare to ask.

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.