Resource Library
Medicare Enrollment Periods
Special Enrollment Period (SEP)
The SEP allows you to make plan changes after a qualifying life event. In most cases, you have 2 full months after a qualifying life event.
The most common qualifying life events include: moving, or leaving retiree, union or COBRA coverage.
(It is important to pay attention to timing to avoid possible late enrollment penalties for Part B and Part D.)
Initial Enrollment Period (IEP)
Your Initial Enrollment Period is a 7-month window that begins 3 months before your birth month, includes your birth month, and ends 3 months after your birth month. If you birthday falls on the 1st of the month, your IEP beings 1 month earlier.
If you are receiving Social Security or Railroad Retirement benefits at 65, you will automatically be enrolled in Part A and Part B.
General Enrollment Period (GEP)
If you miss your Initial Enrollment Period, you are able to enroll in Part A and B in the General Enrollment Period. The GEP lasts from January 1 to March 31 every year. You may choose to enroll in a Medicare Advantage or Part D plan until June 30 of the same year. Late enrollment penalties may apply.
Medicare Annual Enrollment Period (AEP)
Every year from October 15 to December 7, you can change your Medicare Advantage or Part D. The new coverage goes into effect on January 1.
During the Medicare AEP, you can —
Join, switch or drop a Medicare Advantage or Part D prescription drug plan
Switch from Original Medicare to a Medicare Advantage plan, or vice versa
Switch from one Medicare Advantage plan or Part D plan
Medicare Advantage Open Enrollment Period (OEP)
The Medicare Advantage OEP is every year from January 1 to March 31. New coverage goes into effect the first of the month after you made the change.
During the Medicate Advantage OEP, you can —
Switch to another Medicare Advantage plan or return to Original Medicare
Join a stand-alone Part D prescription drug plan if returning to Original Medicare
Enroll in a Medicare Supplement plan
Only make one change during this OEP
What Does Medicare Cost?
Costs for Part A (Hospital Insurance)
Part A Premium
$0 for most people (those who have paid Medicare taxes while working—generally at least 10 years)
If you don’t qualify for premium-free Part A, you might be able to buy it. In 2025, the premium is either $285 or $518 each month, depending on how long you or your spouse worked and paid Medicare taxes.
You also have to sign up for Part B to buy Part A.
If you don’t buy Part A when you’re first eligible (usually when you turn 65), you might pay a penalty.
Part A Deductible
$1,676 for each time you’re admitted to the hospital per benefit period, before Original Medicare (Medicare Part A and Part B) starts to pay. There is no limit to the number of benefit periods you can have.
Inpatient stays (copayments)
Days 1—60: $0 after you pay your Part A deductible
Days 61—90: $419 each day
Days 91—150: $838 each day while using your 60 lifetime reserve days
After day 150: You pay all costs
Costs for Part B (Medical Insurance)
Part B Premium
$185 each month (or higher depending on your income). The amount can change each year. You will pay the premium each month, even if you don’t get any Part B—covered services.
You might pay a penalty if you don’t sign up for Part B when you’re first eligible for Medicare (usually when you turn 65).
Part B Deductible
You will pay $257 before Original Medicare starts to pay. You pay this deductible each year and the amount can change each year.
Costs for services (coinsurance)
You will usually pay 20% of the cost for each Medicare—covered service or item after you’ve paid your deductible.
Late Enrollment Penalties
Part A Late Enrollment Penalty
Some people have to buy Part A because they don’t qualify for premium-free Part A.
If you have to buy Part A, and you don’t buy it when you’re first eligible for Medicare, your monthly premium may go up 10%.
You will have to pay the penalty for twice the number of years you didn’t sign up.
You qualify for premium-free Part A if you or your current or former spouse contributed to Medicare taxes for 10 years.
Part B Late Enrollment Penalty
Generally, you won’t have to pay a Part B penalty if you qualify for a Special Enrollment Period.
You will pay an extra 10% for each year you could have signed up for Part B, but didn’t
You pay the penalty for as long as you have Part B.
You may also pay a higher premium depending on your income.
Part D Late Enrollment Penalty
Generally, you won’t have to pay a Part D penalty if:
You have creditable drug coverage (coverage similar in value to Part D) OR
You qualify for Extra Help
You will pay an extra 1% for each month if you:
Don’t join a Medicare drug plan or Medicare Advantage Plan with Drug Coverage when you first get Medicare.
Go 63 days or more without creditable drug coverage.
You pay the penalty for as long as you have Part D coverage (even if you change plans).
You may also may a higher premium depending on your income.
After you join a Medicare drug plan, the plan will tell you if you have to a penalty and what your premium will will.
Medicare Income-Related Monthly Adjustment Amounts
Depending on your income from two years prior, you may have to pay an additional amount.
