IEP stands for Initial Enrollment Period, the seven-month window when you first become eligible to sign up for Medicare. For most people, this window opens three months before the month you turn 65, includes your birthday month, and closes three months after it. Missing this window can delay your coverage and permanently increase your premiums.
How the 7-Month Window Works
The IEP is built around your 65th birthday. If you turn 65 in June, your IEP runs from March 1 through September 30. During this period, you can enroll in Medicare Part A (hospital coverage) and Part B (outpatient and doctor visits). You can also use this time to choose a Medicare Advantage plan (Part C) or a prescription drug plan (Part D).
When your coverage actually starts depends on which month you sign up. If you enroll during the three months before your birthday month, your coverage begins the month you turn 65. If you wait and enroll during your birthday month or the three months after, coverage doesn’t start until the following month. That gap matters if you need medical care right away, so enrolling early gives you the smoothest transition.
You Might Already Be Enrolled Automatically
Not everyone needs to take action during their IEP. If you’re already receiving Social Security retirement or disability benefits at least four months before you turn 65, Medicare automatically enrolls you in both Part A and Part B. You’ll receive your Medicare card in the mail before your 65th birthday without filing any paperwork.
People with ALS (Lou Gehrig’s disease) get Medicare automatically as soon as their disability benefits begin, with no waiting period. For other disabilities, automatic enrollment happens after 24 months of receiving Social Security disability benefits.
If you’re not collecting Social Security yet, perhaps because you’re still working and delaying benefits, you’ll need to actively sign up. You can do this online through Social Security’s website, by calling 800-772-1213, or by visiting a local Social Security office.
The IEP for People Under 65 With Disabilities
The IEP isn’t only for people turning 65. If you qualify for Medicare through a disability, your IEP follows the same seven-month structure but is anchored to a different date: the 25th month of receiving Social Security disability benefits. Your window starts three months before that 25th month, includes it, and ends three months after. In practice, most people in this situation are automatically enrolled in Parts A and B, so the main decision is whether to add drug coverage or a Medicare Advantage plan.
What Happens If You Miss Your IEP
Missing your IEP without a qualifying reason triggers two consequences: a gap in coverage and a financial penalty that lasts for as long as you have Medicare.
For Part B, the penalty is an extra 10% added to your monthly premium for every full 12-month period you were eligible but didn’t enroll. If you waited two years past your IEP, you’d pay a 20% surcharge on your Part B premium every month, indefinitely. You’d also have to wait for the General Enrollment Period, which runs January through March each year, and your coverage wouldn’t start until July.
Part D has its own penalty. Medicare multiplies 1% of the national base beneficiary premium by the number of full months you went without creditable drug coverage. That amount gets added to your monthly Part D premium, rounded to the nearest ten cents, and recalculated each year as the base premium changes.
Still Working at 65? You Have Options
If you’re covered by a group health plan through your employer (or your spouse’s employer) when you turn 65, you don’t necessarily have to enroll in Part B during your IEP. You can delay Part B without penalty and use a Special Enrollment Period later. This SEP is available while you still have employer coverage based on current employment, plus eight months after that coverage or employment ends, whichever comes first.
There are a few important catches. COBRA coverage and retiree health plans do not count as coverage based on current employment, so neither one protects you from the late penalty. And the SEP only becomes available after your IEP has ended. If you try to enroll during the last three months of your IEP while also qualifying for the SEP, Medicare processes it as an IEP enrollment, which can mean a delay in when your Part B coverage kicks in.
If you miss both the IEP and the SEP, you’re left waiting for the General Enrollment Period with a July coverage start date and a permanent premium penalty. For most people still working with solid employer coverage, the safest move is to enroll in Part A (which is premium-free for most) during the IEP and delay Part B until the employer coverage ends.
How to Enroll
If you’re 65 or older and need to sign up manually, the fastest route is online through the Social Security website, where you can enroll in Part A alone or Parts A and B together. You can also call Social Security at 800-772-1213, available Monday through Friday, 8 a.m. to 7 p.m. in most time zones, with service in English, Spanish, and other languages. TTY users can call 800-325-0778.
Part A and Part B are handled through Social Security. If you want to add a Medicare Advantage plan or Part D drug plan, those are separate enrollments made directly with private insurance companies, typically through Medicare’s plan finder tool or by contacting the plan. Your IEP for Medicare Advantage and Part D coverage aligns with the same seven-month window, so you can coordinate all your choices at once.