I missed the Medicare enrollment deadline — what can I do?

Q: What happens if I miss Medicare enrollment at 65?

With no other qualifying coverage, there will be a gap in coverage and the next opportunity to enroll is the General Enrollment Period, January 1 to March 31, with coverage starting the first day of the month after signing up. A permanent Part B late enrollment penalty of 10% for each full 12 months of delay normally applies. Someone who delayed because they or their spouse were still working and covered by that employer's plan most likely qualifies for an 8-month Special Enrollment Period instead, with no penalty.

Q: Can I change my Medicare plan after December 7?

Only in specific circumstances. Someone already in a Medicare Advantage plan can make one change during the Medicare Advantage Open Enrollment Period, January 1 to March 31. Outside that, a Special Enrollment Period is needed, triggered by events such as moving, losing other coverage, a plan being discontinued, entering a nursing home, or gaining or losing Medicaid or Extra Help. The 5-star plan window is also available where such a plan exists. Dissatisfaction with a plan is not by itself sufficient.

Q: Is the Medicare late enrollment penalty permanent?

In most cases yes. The Part B penalty adds 10% to the premium for each full 12-month period Part B could have been held but was not, and it remains for as long as Part B is held. The Part D penalty adds 1% of the national base beneficiary premium for each full month without creditable drug coverage and also continues indefinitely. Both can be appealed if applied in error, for example where creditable coverage existed but was not recorded.

Q: When does coverage start if I enroll during the General Enrollment Period?

Coverage begins the first day of the month after the month of enrollment. Someone who signs up in February has coverage from March 1. This is a change from the older rule, under which General Enrollment Period coverage did not begin until July 1.

Q: Can I still get a Medigap policy if I missed my open enrollment window?

You can apply at any time, but outside the six-month Medigap open enrollment window and outside a guaranteed-issue right, most states allow the insurer to ask health questions and to decline coverage or charge more. A few states have more generous rules, including annual or birthday-month windows. Whether a guaranteed-issue right exists depends on why the coverage is changing: a plan being discontinued creates one, dissatisfaction does not.

Published by MedicareQuotesForYou. Published August 17, 2026. Last reviewed August 17, 2026.

Short answer

It depends which deadline you missed, and in most cases something is still open. If you missed the December 7 Annual Enrollment Period deadline, you are not without coverage — your existing plan simply continues into the new year. If you are already in a Medicare Advantage plan, you get a second window from January 1 to March 31 to change it once.

If you missed your Initial Enrollment Period around your 65th birthday and have no other coverage, that is the more serious one. You can sign up during the General Enrollment Period, January 1 to March 31, with coverage starting the first day of the month after you enroll. A permanent late enrollment penalty usually applies.

Before assuming you missed anything, check whether a Special Enrollment Period applies to you. Moving house, losing employer or retiree coverage, your plan leaving your area, entering or leaving a nursing home, and qualifying for Medicaid or Extra Help all open enrollment windows outside the normal deadlines. These are far more common than most people realise and they override the calendar.

Which deadline did you miss?

What remains available after each Medicare deadline passes.
The deadline you missed	What it means	What is still open
December 7 — Annual Enrollment Period	You did not change or join a Medicare Advantage or Part D plan for the coming year. Your current coverage rolls over automatically, with whatever changes the plan announced in its Annual Notice of Change.	If you are in a Medicare Advantage plan: the Medicare Advantage Open Enrollment Period, January 1 to March 31. Also the 5-star plan window, and any Special Enrollment Period you qualify for.
Your Initial Enrollment Period at 65	The seven-month window around your 65th birthday. Missing it with no other qualifying coverage means a gap in coverage and usually a permanent penalty.	The General Enrollment Period, January 1 to March 31, with coverage starting the first of the month after you sign up. Check first whether an employer-coverage Special Enrollment Period applies.
March 31 — Medicare Advantage Open Enrollment	You did not use your one allowed change for the year.	Special Enrollment Periods only, plus the 5-star window. Otherwise the next Annual Enrollment Period on October 15.
The 8-month window after employer coverage ended	The Special Enrollment Period for people who delayed Part B while covered by current employment. It runs 8 months from when the employment or the coverage ends, whichever comes first.	The General Enrollment Period, January 1 to March 31. A Part B late enrollment penalty normally applies from this point.
Your 6-month Medigap open enrollment window	The six months beginning when you are 65 or older and enrolled in Part B, during which no insurer can refuse you or charge you more for your health.	You can still apply for Medigap at any time, but in most states the insurer may now ask health questions and can decline you or charge more — unless you have a guaranteed-issue right.

If you missed December 7

This is the least damaging deadline to miss. Nothing lapses: your Medicare Advantage or Part D plan continues into the new year automatically, and Original Medicare continues regardless. What you have lost is the chance to change plans for January 1 — which matters if your plan raised its costs, dropped your drug from its formulary, or lost your doctor from its network.

Three routes remain:

Medicare Advantage Open Enrollment, January 1 to March 31. If you are enrolled in a Medicare Advantage plan on January 1, you may make one change: switch to a different Medicare Advantage plan, or leave for Original Medicare and add a stand-alone Part D plan. The change takes effect the first of the following month. This window does not let someone on Original Medicare join a Medicare Advantage plan, and it does not exist for people with only a stand-alone Part D plan.
The 5-star Special Enrollment Period, December 8 to November 30. If a plan with Medicare's 5-star quality rating is available where you live, you may switch to it once during that period. Five-star plans are not offered everywhere, so this is worth checking rather than assuming.
Any Special Enrollment Period you qualify for — see below. These are the most commonly overlooked route back in.

One thing worth doing straight away if you missed December 7 Find the Annual Notice of Change your plan sent you in September and read what changed for the new year — premium, copays, drug list, network. If your regular prescription moved to a higher tier or came off the formulary entirely, that is worth acting on in the January window rather than absorbing all year. If nothing that matters to you changed, doing nothing is a perfectly reasonable outcome.

If you missed your Initial Enrollment Period at 65

This is the one with real financial consequences, and the first thing to establish is whether you actually missed anything.

You probably did not, if you had coverage from current employment. If you or your spouse were still working and covered by that employer's group health plan, you were most likely entitled to delay Part B without penalty. You then get an 8-month Special Enrollment Period beginning when the employment ends or the coverage ends, whichever happens first. This is the single most common source of unnecessary panic about Medicare deadlines.

Two kinds of coverage do not count for this, and both catch people out. COBRA and retiree coverage are not coverage from current employment. Neither is a Marketplace plan. If you delayed Part B while on COBRA or a retiree plan believing you were protected, the Special Enrollment Period was probably already running without you knowing.

If no Special Enrollment Period applies, the route in is the General Enrollment Period, January 1 to March 31. Coverage begins the first day of the month after you enrol. Once you have Part B, you can then join a Medicare Advantage or Part D plan.

How the late enrollment penalties work

There are two separate penalties, they work differently, and both are usually permanent.

Part B. Your premium increases by 10% for each full 12-month period you could have had Part B but did not sign up. It is added to your monthly premium for as long as you have Part B — in most cases, for life. Delaying by eleven months costs nothing; delaying by thirteen costs 10% permanently.
Part D. Calculated as 1% of the national base beneficiary premium for each full month you went without Part D or other creditable drug coverage after your Initial Enrollment Period. It is added to your Part D premium and, because it is based on a national figure that changes annually, the penalty amount moves each year. Being without drug coverage for less than 63 days in a row does not trigger it.

Both penalties can be appealed if you believe they were applied in error — for example if you did have creditable coverage and it was not recorded. Ask for a reconsideration and provide the evidence of coverage.

There is also one thing that is not a penalty but is often mistaken for one. If you go without Part A when you owe a premium for it, or you enroll late in Part A as someone who has to buy it, different rules apply. Most people never encounter this because Part A is premium-free for them.

The Special Enrollment Periods people forget they qualify for

A Special Enrollment Period (SEP) opens a window outside the normal deadlines because your circumstances changed. They are the reason "I missed the deadline" is so often not the end of the matter. The most common:

You moved to a new address outside your plan's service area, or to an area where new plans are available.
You lost other coverage — employer, union, retiree, COBRA or Medicaid coverage ending.
Your plan is leaving your area, ending its contract with Medicare, or is being discontinued. See what to do when a plan is discontinued, which also opens a guaranteed-issue Medigap right that is easy to miss.
You moved into, live in, or moved out of a nursing home or other institution.
You gained or lost Medicaid, or gained or lost Extra Help with drug costs.
You have full Medicaid together with Medicare, or you have Extra Help. Since January 2025 this works differently from how it used to: there is a monthly window to change a stand-alone Part D plan, and a separate monthly window for full-benefit dual eligibles to join an integrated Dual Eligible Special Needs Plan. The old quarterly window that let anyone in this group change any plan four times a year was removed at the start of 2025 — if you were relying on that, it no longer exists.
You were given incorrect information by a plan, an agent or a federal employee, or the plan violated its contract. This is a real SEP and it is very rarely used, largely because almost nobody knows it exists.
You are enrolled in a plan whose Medicare star rating has fallen to below 3 stars for three consecutive years.

SEPs usually run for a limited time from the qualifying event — commonly two or three months — so the practical advice is to check as soon as the circumstance changes rather than at the next deadline. Our full guide to Medicare enrollment periods sets out each window and its dates.

What you cannot do

Being straightforward about the limits, because a lot of pages are not:

You cannot join a Medicare Advantage plan from Original Medicare between January 1 and March 31. That window is only for people already in a Medicare Advantage plan.
You cannot switch plans simply because you are unhappy with the one you chose, or because your doctor left the network mid-year — a network change on its own does not create a Special Enrollment Period. What is available in that situation is covered here.
You cannot get the Part B late enrollment penalty waived because you did not know about the deadline. Not knowing is not a basis for relief; having been misinformed by an official source may be.
You cannot recover a missed Medigap open enrollment window. Outside it, and outside a guaranteed-issue right, most states allow the insurer to underwrite.

What to do now, in order

Confirm what coverage you currently have and whether there is actually a gap. Many people who believe they missed a deadline have continuing coverage and no gap at all.
Check every Special Enrollment Period against the last twelve months of your life — a move, a job ending, a coverage change, a Medicaid decision. This is where most solutions are found.
If you are in a Medicare Advantage plan and it is January to March, decide whether to use your one allowed change.
If you have no Part B and no SEP applies, plan for the General Enrollment Period, January 1 to March 31, and work out the penalty so there are no surprises.
If cost is the underlying problem, check eligibility for a Medicare Savings Program or Extra Help before anything else — qualifying can both reduce costs and open an enrollment window. See the guide to Medicare on a fixed income.

Frequently asked questions

I missed the December 7 Medicare deadline. What can I do?

Your existing coverage continues into the new year automatically, so you are not left without insurance. If you are enrolled in a Medicare Advantage plan you can make one change between January 1 and March 31, either to a different Medicare Advantage plan or back to Original Medicare with a stand-alone Part D plan. You may also be able to switch to a 5-star plan if one is available where you live, or use a Special Enrollment Period if your circumstances have changed.

What happens if I miss Medicare enrollment at 65?

If you had no other qualifying coverage, you will have a gap in coverage and can next enroll during the General Enrollment Period, January 1 to March 31, with coverage starting the first day of the month after you sign up. A permanent Part B late enrollment penalty of 10% for each full 12 months you delayed normally applies. If you delayed because you or your spouse were still working and covered by that employer's plan, you most likely qualify for an 8-month Special Enrollment Period instead, with no penalty.

Can I change my Medicare plan after December 7?

Only in specific circumstances. If you are already in a Medicare Advantage plan, the Medicare Advantage Open Enrollment Period from January 1 to March 31 allows one change. Outside that, you need a Special Enrollment Period — triggered by events such as moving, losing other coverage, your plan being discontinued, entering a nursing home, or gaining or losing Medicaid or Extra Help — or the 5-star plan window. Simply being dissatisfied with a plan is not enough.

Is the Medicare late enrollment penalty permanent?

In most cases yes. The Part B penalty adds 10% to your premium for each full 12-month period you could have had Part B but did not, and it stays for as long as you have Part B. The Part D penalty adds 1% of the national base beneficiary premium for each full month without creditable drug coverage, and it also continues indefinitely. Both can be appealed if applied in error, for example where creditable coverage existed but was not recorded.

Does COBRA count as coverage for delaying Medicare?

No. COBRA is not coverage from current employment, so it does not let you delay Part B without penalty. The 8-month Special Enrollment Period starts when the employment or the group coverage ends, whichever comes first — not when COBRA ends. Retiree coverage and Marketplace plans do not count either. This is one of the most expensive misunderstandings in Medicare.

When does coverage start if I enroll during the General Enrollment Period?

Coverage begins the first day of the month after the month you enroll. Someone who signs up in February has coverage from March 1. This is a change from the older rule, under which General Enrollment Period coverage did not start until July 1.

Can I still get a Medigap policy if I missed my open enrollment window?

You can apply at any time, but outside your six-month Medigap open enrollment window and outside a guaranteed-issue right, most states allow the insurer to ask health questions and to decline you or charge more. A few states have more generous rules, including annual or birthday-month windows. Whether you have a guaranteed-issue right depends on why your coverage is changing — a plan being discontinued creates one, dissatisfaction does not.

I have both Medicare and Medicaid. Can I change plans any time?

Not as freely as before. The quarterly window that allowed dual eligibles and people with Extra Help to change plans four times a year was removed at the start of 2025. What exists now is a monthly window to change a stand-alone prescription drug plan, and a separate monthly window for full-benefit dual eligibles to enroll in an integrated Dual Eligible Special Needs Plan. Gaining or losing Medicaid or Extra Help also opens its own Special Enrollment Period.

Find out which window is still open to you

Whether a Special Enrollment Period applies depends on the specifics — the dates, the type of coverage you had, and where you live. Tell us a little about yourself and a licensed insurance agent can work through it with you and explain the options available in your area. There is no cost and no obligation.

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Related guides

Medicare enrollment periods and deadlines — every window and its dates
Turning 65: how to sign up for Medicare — the seven-month window and the COBRA, HSA and Marketplace traps
My Medicare Advantage plan is being discontinued — the SEP and the guaranteed-issue Medigap right
How to switch back to Original Medicare — the windows and the underwriting trap