Key Takeaways

• Medicare enrollment is not automatic for everyone. If you’re not receiving Social Security or Railroad Retirement Board benefits at least four months before turning 65, you need to actively sign up.

• Missing your Medicare enrollment window can lead to delays in coverage and permanent late enrollment penalties, particularly for Part B and Part D.

Understanding Who Gets Automatically Enrolled

Medicare enrollment may seem straightforward, but in 2025, many people are surprised to learn that they are not automatically enrolled when they turn 65. The system automatically enrolls only a select group of individuals:

• Those already receiving Social Security or Railroad Retirement Board (RRB) benefits at least four months before their 65th birthday.

• Those under 65 who qualify for Medicare due to disability and have been receiving Social Security Disability Insurance (SSDI) for 24 months.

If you fall outside these categories, the responsibility is on you to initiate your enrollment. Missing that step can be both costly and disruptive.

Know Your Enrollment Windows

If you’re not automatically enrolled, you must understand and act within the enrollment periods set by Medicare.

Initial Enrollment Period (IEP)

This is your first chance to enroll. It’s a 7-month window:

• Begins 3 months before the month you turn 65

• Includes the month of your 65th birthday

• Ends 3 months after your birth month

General Enrollment Period (GEP)

If you miss your Initial Enrollment Period and don’t qualify for a Special Enrollment Period, you can only enroll between January 1 and March 31 each year. Your coverage will begin July 1—a significant delay.

Special Enrollment Period (SEP)

This is only available in specific situations, most commonly if you have employer-sponsored group health insurance at age 65. Once that coverage ends, you typically get 8 months to enroll in Medicare without a penalty.

What Happens If You Miss the Deadline

Failure to enroll during your proper window doesn’t just cause a delay in your Medicare start date—it can also result in permanent late penalties:

• Part B Penalty: You’ll pay an additional 10% for each 12-month period you were eligible but didn’t enroll. This penalty is added to your Part B premium for life.

• Part D Penalty: This penalty applies if you go more than 63 days without creditable prescription drug coverage. It’s calculated based on how long you went without coverage and added permanently to your Part D premium.

When Working Past 65 Affects Enrollment

If you’re still working at 65 and have health insurance through your job or a spouse’s employer, you may be able to delay enrolling in Medicare without penalty. However, this depends on the employer size:

• 20 or more employees: You can usually delay Part B and Part D with no penalty. You’ll be eligible for a Special Enrollment Period once that coverage ends.

• Fewer than 20 employees: Medicare generally becomes your primary payer. Delaying enrollment could leave you without full coverage and may trigger penalties.

You must confirm with your benefits administrator whether your employer coverage qualifies as creditable.

Medicare Part A: What to Know About Free Isn’t Always Free

Part A is premium-free for most people who paid Medicare taxes for at least 10 years (40 quarters). However, if you don’t meet this requirement:

• You may pay up to $518/month for Part A in 2025.

• You should still enroll during your IEP to avoid a penalty that can rise up to 10%, charged for twice the number of years you delayed.

Even if you plan to delay other parts of Medicare, enrolling in Part A (if premium-free) during your IEP can be a strategic move—especially if you’re contributing to a Health Savings Account (HSA), which has limitations when combined with Medicare.

The HSA Conflict You Can’t Ignore

If you’re actively contributing to an HSA and you enroll in any part of Medicare, you must stop HSA contributions six months before your Medicare effective date to avoid tax penalties. Since retroactive Part A coverage is common (up to six months), you must plan carefully.

To stay compliant:

• Stop HSA contributions at least six months before applying for Medicare.

• Consult a financial planner if you’re unsure how Medicare will affect your tax-advantaged accounts.

Social Security Timing Can Affect Medicare Timing

Many people delay Social Security until 66 or 67 to maximize benefits. That’s a smart retirement strategy—but it means you won’t be automatically enrolled in Medicare. You must:

• Proactively sign up for Medicare during your Initial Enrollment Period.

• Use the Social Security website or call to enroll, even if you’re not yet receiving monthly benefits.

Common Enrollment Mistakes to Avoid

Understanding Medicare’s rules in 2025 means avoiding common traps that can lead to penalties or delays. Here are some of the biggest pitfalls:

• Assuming automatic enrollment applies to everyone: As discussed, this only happens if you’re already receiving Social Security or RRB benefits.

• Missing your IEP: This results in late enrollment penalties and delays until July if you must wait for the GEP.

• Assuming employer insurance is always creditable: Especially true for small employers or certain retirement plans.

• Delaying enrollment without verifying rules: Always check with your HR department or benefits advisor before assuming your job coverage allows a Medicare delay.

How to Enroll When It’s Not Automatic

If you need to enroll manually, you have three primary options:

• Online at SSA.gov: Recommended for speed and efficiency.

• By phone: Call Social Security at 1-800-772-1213.

• In person: Visit your local Social Security office (you may need an appointment).

Make sure you have the following ready:

• Proof of age and citizenship (e.g., birth certificate, passport)

• Work history and income documents

• Employer information if delaying due to group health plan coverage

Checking Your Enrollment Status

If you’re unsure whether you’re already enrolled in Medicare:

• Visit MyMedicare.gov to check your enrollment status.

• Call Medicare directly at 1-800-MEDICARE (1-800-633-4227).

This step is especially useful if you’ve recently applied or had a change in your work or retirement status.

Where to Get Help

Medicare can feel overwhelming—especially if you’re not automatically enrolled. Fortunately, several resources are available to help you:

• State Health Insurance Assistance Programs (SHIPs) offer free, unbiased help.

• Licensed agents listed on this website can provide one-on-one assistance tailored to your personal circumstances.

Making Sure You’re Enrolled—And Covered

Medicare is not one-size-fits-all, and automatic enrollment is not a guarantee. If you’re approaching 65 and not receiving Social Security or Railroad Retirement Board benefits, it’s on you to take action. Missing your window can result in lifelong penalties and months without coverage.

Take time now to:

• Confirm your eligibility

• Know your enrollment periods

• Verify your employer’s coverage status

• Act before the deadlines

If you need help sorting through your options, speak to a licensed agent listed on this website. They can walk you through the process and help you avoid costly mistakes.