When the Open Enrollment Period starts and ends
The period covers the first three months of every year. In 2027 it starts on January 1 and ends on March 31. The rule, 42 CFR 422.62(a)(3)(i), describes it as one election during the first 3 months of the year for a person who is enrolled in a Medicare Advantage plan. It comes after Annual Enrollment, which runs from October 15 to December 7 each year, and it has limits of its own: one change, and only for people enrolled in a Medicare Advantage plan. People who are new to Medicare have a version of the window that follows their own start date, explained further down this page.
Who can use it
You can use the Open Enrollment Period if you are enrolled in a Medicare Advantage plan, whether you chose it during Annual Enrollment for a January 1 start or have had it for years. The rule allows one election during the period. People who have Original Medicare cannot use it, and that includes people who have Original Medicare with a stand-alone Part D drug plan: the period is only for people enrolled in a Medicare Advantage plan. Two groups have different rules. People who are new to Medicare have their own three month window, described in the next section. People who live in a long term care facility that counts as an institution under Medicare's rules are not limited to one change (42 CFR 422.62(a)(4)).
If you are new to Medicare and in a Medicare Advantage plan
The rule has a second version for people who are newly eligible. If you are newly entitled to both Part A and Part B and you are enrolled in a Medicare Advantage plan, you can change that election once during your first three months of entitlement. The window begins with the month your Part A and Part B entitlement starts and ends on the last day of the third month. For example, if both start on June 1, your window runs from June 1 to August 31. Because it follows your own start date, this window can fall at any time of year. The choices are the same: another Medicare Advantage plan, or Original Medicare, with a coordinating Part D change if you want one (42 CFR 422.62(a)(3)(ii)).
What you can change to
The period allows one election, in one of two directions. You can move from your Medicare Advantage plan to a different Medicare Advantage plan, with or without drug coverage. Or you can leave Medicare Advantage and return to Original Medicare. With either move you may also make a coordinating Part D election: for example, joining a stand-alone Part D drug plan when you return to Original Medicare, or ending your Part D coverage. The rule calls it a coordinating election because it goes with the Medicare Advantage change (42 CFR 422.62(a)(3)(i)). If you end drug coverage and later go 63 or more days in a row without creditable drug coverage, a Part D late enrollment penalty can apply; what a missed deadline costs explains how it is counted.
What the Open Enrollment Period cannot do
It cannot move you from Original Medicare into a Medicare Advantage plan, because it is only for people already enrolled in one. It cannot switch you from one stand-alone Part D drug plan to another if you have Original Medicare. It cannot be used more than once: after one change the period is used up for that year, although the one change limit does not apply to changes made during Annual Enrollment or during a Special Enrollment Period (42 CFR 422.62(a)(3)(iii)). It cannot be used to join a Medicare Advantage Medical Savings Account (MSA) plan, which you can join only when you are first eligible or during Annual Enrollment (42 CFR 422.62(d)(1)). And it does not let you sign up for Part A or Part B. If you did not sign up for Part B when you were first eligible, the window for that is the General Enrollment Period, which also runs from January 1 to March 31, unless a Special Enrollment Period applies to you; the missed deadline guide explains both.
Other windows that may apply
Some people have more than one option early in the year. If your Medicare Advantage plan was not renewed for 2027, a Special Enrollment Period with its own deadline covers that case; see Medicare plans ending for 2027: your deadlines. A move out of your plan's service area, and some other changes in circumstances, can also open a Special Enrollment Period at any time of year (42 CFR 422.62(b)). If none of these applies, the next window is Annual Enrollment, from October 15 to December 7 each year, for coverage that starts the following January 1.
One change, in the first three months of the year
The Medicare Advantage Open Enrollment Period is narrow by design. It is only for people enrolled in a Medicare Advantage plan, it allows one change, and it closes on March 31. People who are new to Medicare have the same choices in their own first three months. If you are not sure which enrollment period fits your situation, the sections above set out each one.
If you are turning 65, have a Special Enrollment Period, or simply have a question, Lara Goulson can go over it with you by phone or video at your request, at no cost.
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