When exactly does my Initial Enrollment Period start?

Your Initial Enrollment Period begins on the first day of the third month before your 65th birthday month and ends on the last day of the third month after. So if you turn 65 in July, your IEP runs April 1 through October 31. The exception is if your birthday falls on the first of the month — then your IEP shifts one month earlier.

Should I delay Part B if I have employer coverage?

It depends on the size of the employer and the type of coverage. If the employer has 20 or more employees and the coverage is creditable, you generally can delay Part B without penalty and use a Special Enrollment Period later. If the employer has fewer than 20 employees, Medicare typically becomes primary at 65 and delaying Part B can leave you with gaps. Verify creditable status with your employer's benefits administrator before deciding.

What happens if I miss my Initial Enrollment Period?

If you don't qualify for a Special Enrollment Period, you have to wait for the General Enrollment Period (January 1 through March 31). Coverage from a GEP enrollment starts the month after you sign up. There may also be a lifetime late enrollment penalty added to your Part B premium — typically 10% for each full 12-month period you could have had Part B but didn't.

Do I need to do anything if I'm already collecting Social Security?

If you are already collecting Social Security benefits when you become eligible for Medicare, you are typically enrolled automatically in Part A and Part B. You will receive your Medicare card in the mail about three months before your 65th birthday. If you do not want Part B (for example, because you have employer coverage), you can opt out following the instructions that come with the card.

T65 Transition Planning: What to Do 6 Months Before Turning 65 | Empathy Insurance Advisors (Empathy Healthcare Solutions Inc.)

The Initial Enrollment Period

Your IEP is a seven-month window centered on your 65th birthday month. It includes the three months before your birthday month, your birthday month itself, and the three months after. Within this window, you can enroll in Part A, Part B, a Medicare Advantage plan, a Part D prescription drug plan, and (if going the Original Medicare path) a Medigap policy.

When within the IEP you enroll affects when coverage starts. Enrolling in the three months before your birthday month means coverage starts the month you turn 65. Enrolling during or after your birthday month delays coverage by one or more months. Enrolling in the late part of the IEP can delay coverage start by up to three months past your birthday.

Six months out: orienting decisions

The six months before your IEP opens are when most of the real decisions get made. By the time the IEP starts, you want to know which path you are taking — Original Medicare with optional Medigap and a Part D plan, or Medicare Advantage — and roughly which specific plan or plans you are considering.

The orienting decisions in this window typically include:

Original Medicare with Medigap, or Medicare Advantage? The two paths differ in provider access, cost predictability, and out-of-pocket structure. The Medigap guaranteed-issue window is six months from your Part B effective date — a time-bounded factor in the comparison.
How will Part D be handled? Most Medicare Advantage plans bundle Part D. With Original Medicare, Part D is added separately. Either way, the choice depends on the medications you take.
Provider continuity. If you have established provider relationships, check whether they accept Medicare assignment (most do) and whether they participate in any Medicare Advantage plans you are considering.
Travel patterns. Living in or traveling between multiple states can affect which path is more accommodating.

Coordinating with employer coverage

If you or your spouse will still be working when you turn 65, the question of whether to take Part B at 65 depends on the employer plan. Two main scenarios:

Employer with 20 or more employees

If the employer plan covers 20 or more workers, the employer plan generally remains primary and you can delay Part B without a late enrollment penalty as long as the coverage qualifies as creditable. When that employment ends, you have a Special Enrollment Period to enroll in Part B without penalty. Many people in this situation still take Part A at 65 (since most pay no Part A premium) and delay Part B until retirement.

Employer with fewer than 20 employees

For smaller employers, Medicare typically becomes primary when you turn 65 even if you still have employer coverage. Delaying Part B in this case can leave you with gaps and expose you to the late enrollment penalty later. Confirm the situation with your employer's benefits administrator before deciding.

Avoiding late enrollment penalties

Medicare has lifetime late enrollment penalties for Part B and Part D. These penalties are added permanently to your monthly premium for as long as you have Medicare. The penalty for Part B is generally 10% of the standard premium for each full 12-month period you could have had Part B but didn't. The Part D penalty is calculated differently but accrues for each month without creditable drug coverage after eligibility.

The most common cause of these penalties is misjudging whether existing coverage is creditable. “Creditable coverage” has specific meanings for Part B and Part D, and not all employer or other coverage qualifies. When in doubt, get the determination in writing from the plan administrator.

When to start the application process

For most people, applying in the first three months of the IEP — the months before your birthday — gives the cleanest start: coverage begins the month you turn 65. Online applications through SSA.gov take a few weeks to process. Plan and policy applications (Medicare Advantage, Medigap, Part D) typically take days to weeks depending on the carrier and product.

Starting the planning conversation 3-6 months ahead gives time to compare options, run cost projections, and make the application timing fit your situation. Waiting until the last few weeks before turning 65 is feasible but compresses the decision process.

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