Some people may be automatically enrolled in Medicare, while others must enroll during specific periods, such as the initial, general, or open enrollment periods.
To get Medicare benefits, a person must enroll in the federally regulated program.
Knowledge of the Medicare enrollment periods is useful for making decisions about plan changes, preventing the loss of healthcare coverage, and avoiding financial penalties.
Glossary of Medicare terms
We may use a few terms in this article that can be helpful to understand when selecting the best insurance plan:
- Out-of-pocket costs: An out-of-pocket cost is the amount a person must pay for medical care when Medicare does not pay the total cost or offer coverage. These costs can include deductibles, coinsurance, copayments, and premiums.
- Deductible: This is an annual amount a person must spend out of pocket within a certain period before an insurer starts to fund their treatments.
- Coinsurance: This is the percentage of treatment costs that a person must self-fund. For Medicare Part B, this is 20%.
- Copayment: This is a fixed dollar amount a person with insurance pays when receiving certain treatments. For Medicare, this usually applies to prescription drugs.
Medicare enrollment periods include the following:
- initial enrollment period (IEP)
- general enrollment period (GEP)
- open enrollment period (OEP)
- special enrollment period (SEP)
During each enrollment period, a person can take different actions, including signing up for original Medicare (Part A and Part B), changing plans, or enrolling in new ones.
The IEP begins 3 months before a person turns 65, includes the birthday month, and continues for 3 additional months.
For example, a person born on November 5th, 1955, would have an IEP from August 1st, 2020 to February 28th, 2021. The Social Security Administration has a free tool that people can use to learn exactly when their initial enrollment period will be.
During these 7 months, a person can sign up for original Medicare, which includes Part A hospital insurance and Part B medical insurance. A person can also enroll in Medicare Part D, prescription drug coverage, during this period.
In addition, a person may choose to enroll in Medicare Part C, also called Medicare Advantage, rather than original Medicare. The Advantage plans provide an alternative to original Medicare and offer at least the same basic coverage.
The GEP is from January 31st to March 31st each year. If a person did not enroll in original Medicare during their IEP, they can do so during the GEP.
During the GEP, a person can also change their Advantage plan or switch from an Advantage plan to original Medicare. However, a person cannot go from original Medicare to an Advantage plan.
The OEP is from October 15th to December 7th each year. This OEP is also known as the annual enrollment period.
During this time, a person can make changes to their healthcare coverage. They can switch between Advantage plans or change from original Medicare to an Advantage plan.
A person enrolled in original Medicare can also enroll or drop the Medicare Part D plan, which is prescription drug coverage.
Annual notice of change
Each September, Medicare sends out the Annual Notice of Change. This document explains the upcoming plan amendments and may help people decide on changes they want to make during the OEP.
During the Medicare Advantage OEP from January 1st to March 31st, a person can change from an Advantage plan to original Medicare, as long as they are already enrolled in Medicare Advantage.
A person can also switch between Advantage plans or enroll in a Part D prescription drug plan.
Medicare allows SEPs under certain circumstances, such as if someone moves house or loses their current coverage.
The type of changes a person can make and the rules surrounding them are different for the various parts of Medicare, and the SEP covering it.
A person can use this online tool to see if they qualify for a SEP.
Original Medicare
During a SEP, a person can enroll in original Medicare if they are eligible because they are insured with a union, or through a group health plan. They are also eligible if they are employed or their spouse is employed.
The duration of SEP for original Medicare may depend on the person’s specific circumstances.
For example, people who could not enroll when first eligible because they were volunteering abroad have a SEP of 6 months. Formerly incarcerated individuals have a SEP of 12 months after their release.
Advantage plans or Part D
A person can make changes to their Medicare Advantage plans or to their Part D prescription drug coverage during a SEP in various circumstances, such as when they:
- move outside of their current plan’s service area
- return to the United States from abroad
- are released from incarceration
- lose current coverage, for example because they no longer qualify for Medicaid
- leave coverage from their employer or union, including COBRA coverage
The duration and specific time period for SEP vary depending on a person’s circumstances.
5-star special enrollment
Medicare assigns performance ratings to plans based on performance and quality. The ratings vary between one and five stars, with five stars being the best rating.
A person can change to a 5-star plan only once, between December 8th and November 30th.
If a person is in a plan with a rating of less than three stars for three years, they can change to a Medicare Advantage or drug plan at any time.
Depending on the changes a person makes during enrollment periods, there could be costs or penalties. Late enrollment penalties are added to a person’s monthly premium, they are not a one-time fee.
For example, if a person changes from an Advantage plan with drug coverage to a 5‑star Medicare Advantage plan without drug coverage, they may receive a Part D late enrollment penalty if they have to wait until their next enrollment period to get the coverage.
A person may also receive a late enrollment penalty if they do not enroll during their IEP and instead enroll during the OEP.
Part A late enrollment penalty
People may receive premium-free Medicare Part A if they have paid sufficient quarters. However, if a person has to pay for Part A and does not get it when they are initially eligible, they may receive a penalty.
Typically, the penalty means a person’s monthly premium will increase by 10% for double the number of years they did not have Part A.
For example, if a person is eligible for Medicare for 5 years before they enroll, they may have to pay the higher premium for 10 years.
Part B late enrollment penalty
The Medicare Part B penalty increases with the amount of time a person does not have Part B coverage and continues for as long as they are enrolled in Part B.
The penalty is generally a premium increase of 10% for every year a person was eligible but did not enroll in Part B.
Part D late enrollment penalty
A person may have to pay a late enrollment penalty for Part D if they do not join a Medicare drug plan when they initially enroll or do not have prescription drug coverage for a continuous period of 63 days or more after their IEP.
The prescription drug coverage must be creditable or be either Medicare Part D or a Medicare Advantage plan.
The late enrollment penalty depends on the length of time a person does not have the coverage.
Medicare calculates the penalty as 1% of the national base premium, which is $34.70 in 2024. They multiply this amount by the number of full uncovered months, round the total to the nearest $.10, and add it to the Part D premium.
Medicare enrollment periods provide an opportunity for people to enroll in, review, or change their Medicare coverage. Annual changes to Medicare plans are announced each September.
If a person delays enrolling in certain parts of Medicare, they may receive penalties. These penalties are not just a one-time fee and may increase the cost of a person’s monthly premium.
The duration and specific time of year for Medicare enrollment periods will depend on the period and the person’s specific circumstances.