Medicare general enrollment period: dates, coverage start, and penalties

The Medicare general enrollment period runs from January 1 through March 31 each year. It is for people who missed their initial enrollment window and do not qualify for a special enrollment period. Coverage generally starts the month after you sign up, and a late enrollment penalty may apply.

Key facts
General enrollment period	January 1 through March 31The window repeats every year.
Who uses it	People who missed initial enrollmentA special enrollment period may be a better path if one applies.
Coverage start	The month after you sign upA March enrollment generally starts coverage on April 1.
Part B penalty	10% per full yearThe penalty is generally permanent.
Part D penalty	1% per monthA separate penalty can apply to drug coverage.
Not the same as open enrollment	Different purpose and datesOpen enrollment is for changing existing coverage, not first-time Part B enrollment.

What the general enrollment period is

The general enrollment period is the yearly window for people who did not sign up for Part A or Part B when they were first eligible. It runs from January 1 through March 31. A person who uses this window can enroll in Original Medicare, but the coverage does not always start right away.

The window is a safety net, not the preferred path. A person who signs up during the general enrollment period may face a gap in coverage and a late enrollment penalty. The better option, when it is available, is to use the initial enrollment period or a special enrollment period.

The general enrollment period is also not the same as Medicare Open Enrollment in the fall. Open enrollment is for people who already have Medicare and want to change certain coverage. The general enrollment period is for people who need to enroll in Part A or Part B after missing their first chance.

A person who is still working and has qualifying employer coverage usually does not need the general enrollment period. That person may have a special enrollment period when the employer coverage ends. The special enrollment period can allow enrollment without a penalty if the rules are met.

Who should use the general enrollment period

The general enrollment period is for people who missed their initial enrollment period and do not qualify for a special enrollment period. That can include people who did not enroll because they misunderstood the rules, people who lost coverage that did not qualify for a special period, and people who became eligible for Medicare in an earlier year.

A person who had creditable employer coverage may have a special enrollment period instead. A person who had COBRA or retiree coverage may not qualify for the same special period, depending on the circumstances. The type of coverage and the reason it ended matter.

A person who must pay a premium for Part A can also use the general enrollment period. The Part A premium depends on the work record, and the Part B premium and penalty rules apply separately. A person in this situation should check both parts before enrolling.

A person who already has Part A but not Part B can use the general enrollment period to add Part B. The same timing and penalty rules apply. A person who has Part B but not Part A may also use the window, although Part A is premium-free for most people.

The dates and the coverage start

The general enrollment period begins on January 1 and ends on March 31. The dates are fixed, and the window does not depend on a birthday or a work history. A person who enrolls in January generally starts coverage on February 1. A person who enrolls in March generally starts coverage on April 1.

The coverage start is the first day of the month after enrollment. A person who needs care before that date may have a gap. The gap can be costly, especially for hospital care or expensive drugs. A person who is deciding whether to wait should consider the risk of a gap, not just the premium.

The enrollment itself can be handled through Social Security. A person who is not yet receiving Social Security benefits may need to apply separately. The application should be completed before the window closes, and the confirmation should be kept.

A person who misses the general enrollment period generally has to wait until the next year. That can extend a coverage gap and increase the penalty. The cost of waiting is usually higher than the cost of applying during the window.

The penalties that can apply

The Part B late enrollment penalty is generally 10 percent of the standard premium for each full 12-month period a person could have had Part B but did not enroll. The penalty is added to the monthly premium and is generally permanent. A person who waits two full years could pay 20 percent more for Part B.

The Part D late enrollment penalty is separate. It is generally 1 percent of the national base beneficiary premium for each full month without creditable drug coverage. A person who enrolls in Part D after a gap can owe that penalty for as long as the plan is in force.

The penalties are not reduced by enrolling during the general enrollment period. The window makes enrollment possible, but it does not erase the months without coverage. A person who had creditable coverage during the gap may be able to avoid the penalty, but the evidence must support the claim.

A person who receives a penalty notice should check the dates and the coverage records. If the notice is wrong, the person can ask for a review. The plan and Medicare are the official sources for the review process.

Part D and Medigap during the window

A person who enrolls in Part B during the general enrollment period may also need drug coverage. A Part D plan can be chosen during the same period, but the plan has its own enrollment rules. A person who had no creditable coverage may owe a Part D penalty.

A Medigap policy is separate from Medicare. The Medigap open enrollment period is generally tied to the start of Part B, not to the general enrollment period. A person who delayed Part B may have a different Medigap window than someone who enrolled at 65. The rules vary by state and by the policy.

A person who chooses a Medicare Advantage plan instead of Original Medicare should compare the plan's network and drug coverage. The general enrollment period is about getting into Part A and Part B. The plan choice comes after that, and it should be based on the person's needs.

A person who is not sure which path applies should contact the State Health Insurance Assistance Program or Social Security. The general enrollment period is simple in dates but complicated in consequences. A short conversation can prevent a long penalty.

Worked example

Consider a person who missed the initial enrollment period and enrolls in Part B on February 10. The coverage generally starts on March 1. The person pays the Part B premium from that point and may owe a penalty for the months without coverage.

A second person enrolls on March 20. The coverage generally starts on April 1. The one-month difference in enrollment creates a one-month difference in the coverage start. If the person needs care in March, the gap can matter.

Now suppose the first person went two full years without Part B and did not have creditable coverage. The Part B penalty could be 20% of the standard premium, added permanently. The exact dollar amount depends on the standard premium in each year.

The example does not include the Part D penalty or the cost of care during the gap. Those are separate. The purpose is to show that the general enrollment period solves the enrollment problem but not the cost of waiting.

Three honest caveats

The general enrollment period is not the best option if a special enrollment period applies. Check the special rules first.
Coverage starts the month after enrollment, so a March application can leave a gap through the end of March.
The penalties are generally permanent and can apply to both Part B and Part D. The window does not remove them.

Frequently asked questions

When is the general enrollment period?

It runs from January 1 through March 31 each year.

When does coverage start after I enroll?

Coverage generally starts the first day of the month after you sign up. A March enrollment usually starts on April 1.

Can I avoid the late enrollment penalty?

You may avoid it if you had creditable coverage during the gap or qualify for a special enrollment period. Otherwise, the penalty can apply.

Is the general enrollment period the same as open enrollment?

No. Open enrollment in the fall is for changing existing coverage. The general enrollment period is for enrolling in Part A or Part B after missing the first chance.

Can I enroll in Part D during the general enrollment period?

You can choose drug coverage, but Part D has its own rules and a separate late enrollment penalty may apply.

What if I miss the general enrollment period?

You generally have to wait until the next year, which can extend a coverage gap and increase the penalty.

Source table

Figure	Value used	Official source
General enrollment dates	January 1 through March 31	Medicare.gov avoid penaltiesChecked October 28, 2026
Part B penalty	10% per full year	Medicare.gov avoid penaltiesChecked October 28, 2026
Part D penalty	1% per uncovered month	Medicare.gov Part D costsChecked October 28, 2026
Enrollment help	Social Security application	SSA Medicare sign-upChecked October 28, 2026

What to do next

If you missed your first window, check whether a special enrollment period applies before you wait for the general enrollment period. If you have employer coverage, confirm the employer size and whether the coverage is creditable. The Part B late enrollment penalty calculator shows how the penalty grows, and the Medicare initial enrollment period guide explains the window you may have missed.

Medicare general enrollment period