Medicare Part B is not automatic — you have to choose it, and the choice matters

Medicare Part B covers doctor visits, outpatient care, lab work, and medical equipment. It is not included in Part A (hospital insurance) and does not start unless you sign up for it. If you turn 65 and do nothing, you will have Part A but not Part B. You can refuse Part B, but doing so usually costs you more later if you change your mind.

The real question is not whether Part B is mandatory, but whether skipping it makes financial sense for you. Most people end up taking it because the penalty for waiting is steep and permanent.

Key Takeaways

  • Part B is optional at 65, but if you do not take it when first may be able to access, you pay a 10 percent higher premium for each year you waited — and this penalty stays with you for life.
  • You can turn down Part B without penalty only if you have creditable coverage from an employer or union plan that is still active.
  • If you miss the sign-up window and do not have employer coverage, you can only join Part B during the General Enrollment Period (January 1 to March 31 each year), and the penalty applies.
  • Part B costs a monthly premium (the amount varies by income) plus a yearly deductible and coinsurance, so the total out-of-pocket cost depends on how much medical care you use.
  • Working past 65 and staying on an employer plan is the only common way to delay Part B without penalty.

When you can legally skip Part B without penalty

You can turn down Part B at 65 without facing a lifetime penalty if you have creditable coverage — health insurance through a current employer or union that covers at least as much as Medicare Part B does. The coverage must be active, meaning you are still working or your spouse is still working and you are covered under their plan.

Creditable coverage includes employer group health plans, union plans, and coverage through a spouse's employer. It does not include retiree coverage (coverage after you have left the job), Medicaid, or individual policies you bought on your own. If you have any doubt whether your plan counts as creditable, call the plan administrator or your employer's benefits office and ask them directly.

Once you lose that employer coverage — because you retire, your spouse retires, or the plan ends — you have a special enrollment period of 8 months to join Part B without penalty. After that window closes, the penalty applies if you did not take Part B when you first became may be able to access at 65.

The lifetime penalty for waiting too long

If you do not take Part B when you first become may be able to access at 65, and you do not have creditable employer coverage, Medicare charges you a permanent late enrollment penalty. The penalty is 10 percent of the standard Part B premium for each full year you were may be able to access but did not sign up.

Here is what that means in practice: if the standard Part B premium is $165 per month and you wait 3 years to join, you pay an extra $49.50 per month (10 percent × 3 years × $165) for as long as you have Part B. That extra amount never goes away, even if you move to a different plan or if the standard premium changes. The penalty is calculated once and locked in.

The only exception is if you have a valid reason for missing the important date — for example, you were out of the country for more than 6 months, or Medicare gave you incorrect information in writing. These exceptions are rare and require you to contact Social Security and provide documentation.

How Part B premiums and costs work

Part B has two costs: the monthly premium and the annual deductible. The monthly premium is income-based, meaning higher earners pay more. In 2024, the standard premium ranges from about $165 to $560 per month depending on your income from two years prior. Social Security adjusts these amounts each year.

On top of the premium, you pay a yearly deductible (currently $240) before Medicare starts to pay its share. After you meet the deductible, you typically pay 20 percent of the cost of covered services, and Medicare pays 80 percent. There is no out-of-pocket maximum under Original Medicare Part B, which means your costs can add up if you need a lot of care.

Many people buy a Medigap (supplemental insurance) or Medicare Advantage plan to reduce these out-of-pocket costs. Medigap plans cover some or all of the 20 percent coinsurance you would otherwise pay. Medicare Advantage plans have their own deductibles and copays but often include prescription drug coverage and may have an out-of-pocket maximum.

What happens if you miss the initial enrollment window

Your initial enrollment period is the 7-month window that starts 3 months before the month you turn 65 and ends 3 months after. If you do not sign up during this time and you do not have creditable employer coverage, you cannot join Part B until the next General Enrollment Period, which runs January 1 to March 31 each year.

If you join during the General Enrollment Period, your coverage does not start until July 1 of that year. That means if you miss your initial window in, say, June 2024, you cannot join until January 2025 at the earliest, and coverage would not begin until July 2025. During those months without Part B, you are responsible for the full cost of any doctor visits or outpatient services.

The late enrollment penalty applies to anyone who joins outside their initial enrollment period and did not have creditable coverage. This penalty is permanent and compounds the longer you wait.

Part B and other Medicare decisions

Choosing Part B is separate from choosing Part D (prescription drug coverage) and separate from deciding between Original Medicare and Medicare Advantage. You can have Part A without Part B, but if you take Part B, you then decide whether to use Original Medicare (Parts A and B) with a Medigap plan, or to switch to a Medicare Advantage plan.

If you have Part A but not Part B, you can still use Part A benefits for hospital stays, skilled nursing, and hospice. You just pay out of pocket for doctor visits and outpatient care unless you have other insurance. Some people in this situation use urgent care clinics or community health centers to keep costs down, though these do not count toward any Medicare deductible.

If you later decide to take Part B, the decision to add it does not change your Part A coverage or your prescription drug plan. You straightforward enroll in Part B during an open enrollment period and start paying the premium.

Special situations: working past 65 and other exceptions

If you are still working at 65 and covered by your employer's health plan, you can delay Part B without penalty. This is the most common reason people skip Part B at 65. Once you retire or lose that coverage, you have 8 months to join Part B without penalty.

If you are receiving Social Security benefits when you turn 65, Part B is automatically enrolled unless you actively decline it. If you are not yet receiving Social Security, you must sign up for Part B yourself during your initial enrollment period, even if you have employer coverage.

Non-citizens who are not yet permanent residents may have restrictions on Part B enrollment. If you are in this situation, contact Social Security directly to understand your options.

Frequently Asked Questions

Can I take Part A without Part B?

Yes. Part A (hospital insurance) and Part B (medical insurance) are separate. You can have Part A alone and pay out of pocket for doctor visits, or you can add Part B later. However, if you wait past your initial enrollment period without creditable coverage, you will owe a lifetime penalty when you do join.

What if I do not go to the doctor much — is Part B worth it?

That depends on your income, your health, and your other coverage. Part B costs a monthly premium plus a deductible, so if you rarely see a doctor, those costs may outweigh the benefit. However, the penalty for waiting is steep and permanent, so most people find it cheaper to take Part B now than to skip it and pay a penalty later.

Can I drop Part B after I sign up?

Yes, you can drop Part B during the General Enrollment Period (January 1 to March 31). However, if you drop it and later want to rejoin, you will owe the late enrollment penalty unless you have a valid reason for the gap. It is usually better to keep Part B once you have it.

Does my employer have to tell me if my coverage is creditable?

Employers are required to provide a notice stating whether their plan is creditable coverage for Medicare purposes. If you do not receive this notice, ask your benefits office or HR department directly. Keep this notice — you may need it to prove you had creditable coverage if you join Part B later.

What if I turned 65 years ago and never signed up for Part B?

You can join Part B during the General Enrollment Period (January 1 to March 31), and coverage begins July 1. You will owe a late enrollment penalty based on how many years have passed since you first became may be able to access. Contact Social Security to enroll and learn the exact penalty amount.