You can cancel Medicare Part B, but the process depends on whether you want to stop it temporarily or permanently, and when you act

Cancelling Medicare Part B (medical insurance) is not automatic — you have to contact Medicare directly and request it in writing. The timing matters: if you cancel during the wrong period, you may face a permanent penalty on your premiums. You can cancel Part B while keeping Part A (hospital insurance), or you can drop both. The most common reason people cancel is to switch to a retiree health plan from a former employer, but you can also cancel if you have coverage through a current job.

Medicare processes cancellations through your local Social Security office or by mail to the Medicare address. The cancellation takes effect on the first day of the month after Medicare receives your request. If you change your mind, you have a window to re-enroll without penalty, but that window is limited.

Key Takeaways

  • You must submit a written request to cancel Part B — a phone call alone will not end your coverage.
  • Cancellation takes effect on the first of the month after Medicare receives your request, not the day you submit it.
  • If you cancel outside the allowed periods, you may owe a 10% premium increase for each year you were without Part B coverage.
  • You can cancel Part B while keeping Part A, or drop both parts at the same time.
  • If you cancel to join a retiree health plan or because you have employer coverage, keep proof of that coverage — you will need it to re-enroll without penalty later.

When you can cancel Part B without a penalty

You can cancel Part B without facing a premium penalty if you have creditable coverage — meaning health insurance from a current employer, a union, a retiree health plan, TRICARE, the Veterans Administration, or certain other sources. Creditable coverage must be as good as or better than Medicare Part B. If you have this coverage, you can cancel Part B at any time and re-enroll later without penalty.

The key is documentation. Before you cancel, get a letter from your employer or plan stating that your coverage is creditable and the dates it covers you. Keep this letter. When you re-enroll in Part B later, Medicare will ask for proof that you had creditable coverage during the time you were not enrolled. Without it, Medicare will assume you went uninsured and will calculate a penalty.

If you do not have creditable coverage and you cancel Part B, you enter what Medicare calls a gap period. If that gap lasts more than 63 days, you will owe a penalty when you re-enroll. The penalty is 10% of the Part B premium for each full year you were without coverage, and it is permanent — you pay it for the rest of your life.

How to submit a cancellation request

You must request cancellation in writing. Phone calls do not count. You have three ways to submit your request:

  1. Mail a letter to Medicare. Address it to Centers for Medicare & Medicaid Services, 7500 Security Boulevard, Baltimore, MD 21244-1850. Include your name, Medicare number, date of birth, signature, and a statement that you want to cancel Part B (and Part A, if you want to cancel both). State the date you want the cancellation to take effect — it will be the first of the month after Medicare receives your letter.
  2. Visit your local Social Security office in person. Bring your Medicare card and a photo ID. Tell the staff member you want to cancel Part B. They will have you sign a form (CMS-1763) and will give you a receipt showing the date you submitted the request.
  3. Call Social Security at 1-800-772-1213 and ask them to mail you the cancellation form. You fill it out, sign it, and mail it back. This route takes longer because of the back-and-forth by mail.

The in-person route at Social Security is the fastest and gives you a dated receipt. If you mail a letter, keep a copy and consider sending it certified mail so you have proof of the date Medicare received it. The cancellation takes effect on the first day of the month after the date Medicare receives your request — not the date you submit it.

What happens to your premiums and coverage after cancellation

Once your Part B cancellation takes effect, Medicare stops billing you for Part B premiums. If you were having premiums deducted from your Social Security check, that deduction stops. If you were paying by mail or online, you no longer owe those payments.

Your Part B coverage ends on the last day of the month before the cancellation takes effect. After that date, Medicare Part B does not cover doctor visits, outpatient care, lab work, or medical equipment. If you have a doctor's appointment scheduled for after your cancellation date, you will be responsible for the full cost unless you have other insurance.

If you cancelled Part B but kept Part A, your hospital insurance continues. Part A covers inpatient hospital stays, skilled nursing facility care, and some home health services. You will still receive a Medicare card, and it will show that you have Part A only.

Re-enrolling in Part B after cancellation

If you cancelled Part B and later want to re-enroll, you can do so during the General Enrollment Period, which runs from January 1 to March 31 each year. Coverage begins on July 1 of that year. This is the standard route and applies to most people.

If you cancelled because you had creditable coverage from an employer or retiree plan, you may be able to re-enroll during a Special Enrollment Period without waiting for the General Enrollment Period. This applies if your creditable coverage ends or if you lose it involuntarily. You have eight months from the date your creditable coverage ends to re-enroll without penalty. You must show Medicare proof that you had creditable coverage during the time you were not enrolled in Part B.

If you re-enroll outside these windows and you do not have proof of creditable coverage, Medicare will calculate a penalty. The penalty is 10% of the Part B premium for each full year you were without Part B coverage. This penalty is added to your premium permanently.

Common mistakes to avoid

The biggest mistake is assuming a phone call cancels your coverage. It does not. You must submit a written request. If you call Medicare or Social Security and tell them you want to cancel, ask them to mail you the form or to schedule an in-person appointment. Do not assume the conversation itself has cancelled your Part B.

Another mistake is cancelling Part B without having creditable coverage in place. If you plan to cancel because you are switching to a retiree health plan, make sure that plan is active and covers you before your Part B cancellation takes effect. If there is a gap between when Part B ends and when the new plan begins, you may owe a penalty.

A third mistake is not keeping proof of creditable coverage. If you cancel Part B because you have employer coverage, get a letter from your employer or plan administrator stating that your coverage is creditable. Store this letter with your Medicare documents. You will need it if you re-enroll in Part B later.

Finally, do not cancel Part A by accident. If you want to cancel only Part B and keep hospital insurance, say that clearly in your written request. If you want to cancel both, say that. Ambiguous requests can lead to confusion about which parts you actually cancelled.

If you need help with the cancellation process

Medicare has a phone line at 1-800-MEDICARE (1-800-633-4227). They can answer questions about cancellation and can mail you the cancellation form. State Health Insurance information Programs (SHIPs) offer free counseling about Medicare changes. You can find your state's SHIP by calling 1-877-839-2675 or visiting the SHIP website.

If you are cancelling because you have retiree health coverage, your former employer's benefits office can tell you whether your coverage is creditable and can provide the letter you need. If you are cancelling because you have current employer coverage, your HR or benefits department can do the same.

Frequently Asked Questions

Can I cancel Part B but keep Part A?

Yes. When you submit your cancellation request, specify that you want to cancel Part B only. Part A (hospital insurance) will continue. Your Medicare card will show that you have Part A coverage only.

What if I cancel Part B and then change my mind a month later?

You can re-enroll during the General Enrollment Period (January 1 to March 31), with coverage starting July 1. If you cancelled because you had creditable coverage that has now ended, you may may have access to for a Special Enrollment Period, which gives you eight months to re-enroll without penalty. Otherwise, you will owe a penalty if you were without Part B for more than 63 days.

Do I have to cancel Part B if I have employer coverage?

No. You can keep both Part B and employer coverage. However, if your employer coverage is primary, you may want to cancel Part B to avoid paying two premiums. Check with your employer's benefits office about whether cancelling Part B makes sense for your situation.

Will I owe a penalty if I cancel Part B to join a retiree health plan?

No, as long as the retiree plan is creditable coverage and you have proof of it. Get a letter from the plan stating it is creditable before you cancel Part B. When you re-enroll in Part B later, provide this letter to Medicare.

How long does it take for my Part B cancellation to take effect?

Cancellation takes effect on the first day of the month after Medicare receives your written request. If you submit your request on March 15, your cancellation takes effect on May 1. If you submit it on April 1, it takes effect on May 1. Processing usually takes two to four weeks after Medicare receives your request.