Should I Enroll in Medicare Insurance When I’m First Eligible?

You may see phrases like “Medicare penalty” or “late-enrollment penalty” while researching the Medicare program. If you don’t sign up for certain parts of the Medicare program in the proper time, these penalties may apply to you.

As you know, most people age into Medicare insurance eligibility when they turn 65. Your Initial Enrollment Period (IEP) starts three months before the month of your 65th birthday, continues through your birth month, and lasts for three months after it, unless your birthday is on the first of a month. In this case, your IEP starts one month earlier and ends one month earlier.

So, if you don’t enroll in Medicare insurance when you’re first eligible, what’s the damage? The penalties differ depending on which part of the Medicare program you are enrolling in.

Part A

If you’re collecting Social Security or Railroad Retirement Board (RRB) benefits, you’ll be automatically enrolled in Medicare Part A and don’t need to fear any enrollment penalties. If you delay receiving Social Security benefits past age 65, you’ll need to sign up for Original Medicare yourself or find a local licensed sales agent to help.

You’re eligible for premium-free Part A if you or a spouse paid Medicare program taxes for at least 40 quarters (10 years) before enrollment.

The Penalty

If you’re not eligible for premium-free Medicare Part A and you didn’t enroll during your IEP, your monthly premium may grow by 10 percent for twice the number of years you could have been enrolled in Part A. For example, if you could have signed up when you were 65, but waited until you were 69 (four years), the penalty will last for eight years.

To avoid a penalty for Part A, you should apply for Medicare insurance online or visit your local Social Security office during your IEP if you don’t already receive Social Security or RRB benefits.

Part B

Just like Part A, if you’re collecting Social Security or RRB benefits when you turn 65, you’ll be automatically enrolled in Medicare Part B. You can turn down Part B benefits at this time by contacting Social Security or following the instructions in your Medicare insurance welcome packet to return your card. However, you should only do this if you’re still on qualified group health plan coverage through your or your spouse’s employer.

The Penalty

If you fail to enroll in Part B during your IEP and don’t have qualified group health plan coverage, your monthly premium may rise 10 percent for each 12-month cycle that you were not enrolled. That means if you waited 24 months (two years) to enroll in Part B after you were able, you may receive a 20-percent penalty on top of your monthly premium for as long as you have the plan. If you drop your Part B plan, only to sign up again later, you may still have the penalty.

If you don’t sign up when you’re first eligible and you’re not eligible for a Special Enrollment Period (covered below), you may also have to wait until the General Enrollment Period to enroll in Part B. This period runs from January 1 to March 31. If this happens, your coverage will start the month after you sign up.

To avoid a penalty for Part B, you should apply for Medicare insurance online or visit your local Social Security office during your IEP if you don’t already receive Social Security or RRB benefits or have qualified group health plan coverage from an employer.

Part D

If you go without creditable prescription drug coverage for any continuous period of 63 days or more, you may be subject to a premium penalty when you eventually buy a prescription drug plan.

Acceptable forms of coverage could include drug coverage from a current or former employer or union, TRICARE or VA benefits.

The Penalty

The size of your Part D penalty grows by one percent each month you go without creditable coverage. If you are without coverage for 25 months, your penalty will be 25 percent.

Twenty-five percent of what? Your penalty is based on the “national base beneficiary premium” ($38.99 in 2026). In this case, your penalty will be $9.70 a month (38.99 x .25 = 9.7475, rounded to the nearest $.10). The national base beneficiary premium may change each year (it was $36.78 in 2025), and the penalty will change with it.

To avoid a penalty for Part D, you should join a Medicare drug insurance plan during your IEP to prevent going 63 days or more in a row without creditable drug coverage.

Special Enrollment Periods

The common theme in avoiding a Medicare insurance penalty is to get coverage during your IEP. However, as we noted, there are some special exceptions that allow you to delay enrollment past your IEP without a penalty.

If you’re still covered under a qualified group health plan from your employer, you have a Special Enrollment Period (SEP) to enroll in Original Medicare at any time as long as you or your spouse is working and your health plan is based on that employment.

Additionally, you have an eight-month SEP to enroll in Original Medicare that begins the month after your employment or the health plan attached to that employment ends (whichever comes first).

Extra Help and Appeals

If you have a limited income or resources, your state may help you afford Original Medicare. You can also apply for Extra Help for Part D coverage.

If you disagree with a Part D penalty, you can ask for a reconsideration. Your drug plan will detail the reconsideration process. You must start the process within 60 days of learning about your penalty. You should also send any supporting evidence that you had creditable coverage along with a completed reconsideration form.

When does your coverage start after you sign up?

Knowing when to enroll in Medicare is only half the picture. You also need to know when coverage actually begins, because a late sign-up inside your window can still leave a gap. Medicare says coverage always starts on the first of the month.

The month you sign up decides which first of the month that is. Here is how it works for Part B, and for Part A if you have to pay a premium for it.

Part A with no premium works a little differently. It starts the month you turn 65. If your birthday falls on the 1st, it starts the month before. If you sign up for Part A after 65, coverage can reach back up to 6 months, but never earlier than the month you turned 65, per Medicare.gov.

The takeaway: if you want Part B to start on day one, sign up in the 3 months before your birthday month.

When to enroll in Medicare if you’re still working

Many people keep working past 65. If you or your spouse have group health coverage through a current job, Medicare says you can delay Part B without a late penalty. You then sign up when the job or the job coverage ends, whichever comes first.

At that point you get a Special Enrollment Period. It lasts 8 months after the job or the group coverage ends, whichever happens first. Medicare also notes that if you sign up while still working, or within the first full month after job coverage ends, you can choose to delay your Part B start by up to 3 months, according to Medicare.gov.

A few points people often miss:

• The coverage must come from current work. Retiree coverage and COBRA are not the same thing (more on that below).
• Health Savings Accounts. If you have an HSA, Medicare says you and your employer should stop contributions about 6 months before you retire or apply for Social Security or Railroad Retirement benefits, to avoid a tax penalty (Medicare.gov).
• Part A timing. If you don’t have to pay a Part A premium, you can enroll in Part A at 65 or later.

For a deeper look, see our guide to working and Medicare.

Is enrollment automatic, or do you have to sign up?

It depends on whether you already get Social Security or Railroad Retirement Board (RRB) benefits. Medicare.gov says you are enrolled in Parts A and B automatically if you get Social Security benefits at least 4 months before you turn 65. Your card comes in the mail about 3 months before coverage starts (Medicare.gov).

If you aren’t getting benefits yet, nothing happens on its own. You need to contact Social Security to sign up. Medicare.gov lists these ways to do it:

• Online at ssa.gov/medicare/sign-up, which Medicare calls the easiest and fastest way. You’ll need a my Social Security account.
• In person at your local Social Security office.
• By phone for disability applications at 1-800-772-1213 (TTY 1-800-325-0778).
• Through the RRB at 1-877-772-5772 if you or your spouse worked for a railroad.

One more case: if you live in Puerto Rico or outside the U.S., Part A is automatic, but you must sign up for Part B yourself. After you sign up, your welcome package and card usually arrive about 2 weeks later, per Medicare.gov.

What does waiting cost in 2026?

Late penalties are added to your monthly premium. For most people, Medicare says they last for as long as you have that coverage. Here are examples using the 2026 Part B standard premium of $202.90 and the 2026 Part D national base premium of $38.99.

The Part D penalty is figured on the national base premium, not your plan’s premium. That base amount can change each year, so the dollar figure can change too. Medicare says the penalty stays with you even if you switch drug plans.

There are ways to avoid these charges. Medicare says you generally won’t pay a Part B penalty if you qualify for a Special Enrollment Period or enroll in a Medicare Savings Program. You generally won’t pay a Part D penalty if you had creditable drug coverage or qualify for Extra Help (Medicare.gov). Our Part D penalty guide explains the math in more detail.

What if you have COBRA, retiree or Marketplace coverage?

These three types of coverage trip people up more than anything else. None of them works like current job coverage.

COBRA. Medicare says COBRA doesn’t extend your time to sign up for Medicare. Your 8-month window starts when the job or job coverage ends, even if you pick COBRA. If you have Medicare first and then get COBRA, COBRA pays after Medicare, unless you have End-Stage Renal Disease (ESRD).

Retiree coverage. Medicare lists the end of COBRA or retiree coverage among situations that don’t qualify you for a Special Enrollment Period. Many retiree plans also expect you to have both Part A and Part B. Ask your benefits administrator before you join any Medicare plan, since joining one your former employer doesn’t offer could cost you your retiree coverage.

Marketplace coverage. Medicare.gov says to sign up for Medicare when you’re first eligible, even if you have a Marketplace plan. Once you can get Part A without a premium, you no longer qualify for Marketplace help with premiums. If you keep getting that help, you may have to pay some or all of it back at tax time. End your Marketplace plan before Medicare starts so the two don’t overlap.

Other special enrollment periods for Part B

Job coverage isn’t the only reason you might sign up outside your first window. Medicare lists several other Special Enrollment Periods for Part A and Part B. Each has its own end date.

Medicare notes that some of these periods apply only to events on or after January 1, 2023. If none fits, you may be able to ask Social Security about an “exceptional conditions” period. Coverage under these windows generally starts the month after you sign up.

When to enroll in Medicare Advantage, Part D or a Medigap plan

Parts A and B are only the first step. The other parts of Medicare have their own rules about timing.

Medicare Advantage and Part D. You can join during the same 7-month Initial Enrollment Period. A Medicare Advantage Plan requires both Part A and Part B. A drug plan requires Part A or Part B. If you ask to join before your Part A or B starts, plan coverage starts the same day. If you ask later, it starts the first of the month after the plan gets your request (Medicare.gov).

If you add Part B later. Say you took Part A at 65 and delayed Part B because of job coverage. Medicare gives you a window to join a Medicare Advantage Plan for 2 months after you have both parts for the first time. If you join a plan in that window, you can still change plans within the first 3 months you have Parts A and B, per Medicare.gov.

Medigap. Your Medigap Open Enrollment Period is a 6-month window. It starts the first day of the month you’re 65 or older and signed up for Part B. After it ends, Medicare says there’s no federal guarantee a company will sell you a policy, and it may cost more due to health problems.

This matters if you’re working. Medigap open enrollment starts when Part B starts, even if you sign up while you still have job coverage. Medicare notes that job coverage often works like Medigap, so you may not need a Medigap policy yet. Delaying Part B can preserve that window for later. In Massachusetts, Medigap uses a different plan structure; see our Massachusetts Medicare supplement guide.

A sample timeline: when to enroll in Medicare at 65

Hypothetical example. Dana turns 65 on July 15. She isn’t getting Social Security yet and has no job coverage. Here is how the Medicare.gov rules above would apply to her.

1. April 1: Her 7-month Initial Enrollment Period opens. It runs through October 31.
2. April to June: If she signs up for Parts A and B now, both start July 1.
3. July: If she waits until her birthday month, Part B starts August 1. Part A, with no premium, still starts July 1.
4. Same window: She can join a drug plan or a Medicare Advantage Plan. If she does this before July 1, the plan starts with her Part A and B.
5. July 1 to December 31: If her Part B starts July 1, this is her 6-month Medigap Open Enrollment Period.
6. After October 31: Her first window closes. Without a Special Enrollment Period, she would wait for the General Enrollment Period and could owe a late penalty.

Your dates will be different. The safest way to decide when to enroll in Medicare is to write down your birthday month, any job coverage end date, and your drug coverage status, then check each against the rules above. A licensed agent can walk through your dates with you, and Medicare.gov and 1-800-MEDICARE are always available too.

Nobody wants the first time they hear about Medicare insurance penalties to be when they’re receiving them. Knowing what causes these penalties is an important step in avoiding them.

Read more: Medicare.gov. Avoid late enrollment penalties. – https://www.medicare.gov/basics/costs/medicare-costs/avoid-penalties

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