2027 Annual Enrollment Period: dates and what to compare

What this window is

The Medicare Annual Enrollment Period is also called Open Enrollment or the Annual Coordinated Election Period. It is the once-a-year window when people who already have Medicare can make many Medicare Advantage and Part D changes for the next calendar year. For 2027 coverage, that window is in fall 2026. The plan generally must receive the request by December 7, 2026, for a change that starts January 1, 2027. Confirm the rule that fits you on Medicare.gov.

Why review even if you want to stay

Medicare Advantage and Part D plans can change every year. Premiums, copays, deductibles, drug lists, pharmacy networks, doctor networks, extra benefits, and prior authorization rules in 2027 may not match 2026. If you already have one of those plans, read the Annual Notice of Change before you decide to keep it. Why the notice matters.

Dates for 2027 coverage

December 7, 2026 is the deadline that matters most. In most cases it is the last day to join, switch, or drop Medicare Advantage or stand-alone Part D coverage for the 2027 calendar year during Annual Enrollment.

• October 1, 2026: start reading plan notices. Medicare treats October 1 as a preparation date, before enrollment opens.
• October 15, 2026: Annual Enrollment begins (October 15 – December 7). This is when many 2027 plan changes can be submitted.
• December 7, 2026: Annual Enrollment ends. The plan should have the request by this date for a January 1 start.
• January 1, 2027: new coverage begins, or your current plan renews with its 2027 changes if you stayed.
• January 1 through March 31, 2027: the Medicare Advantage Open Enrollment Period (January 1 – March 31). It applies only if you are already in a Medicare Advantage plan, and it allows one limited change. It is not a second full Annual Enrollment.

Two meanings of “open enrollment 2027”

People use that phrase for two different windows. Annual Enrollment for 2027 coverage happens in fall 2026. The Medicare Advantage Open Enrollment Period happens from January 1 to March 31, 2027, and only for people already in a Medicare Advantage plan. Mixing them up is a common way to miss December 7.

Changes you can make

What you can do depends on the coverage you have now. People with Original Medicare can join, drop, or switch a stand-alone Part D plan. People in Medicare Advantage can switch Advantage plans, or return to Original Medicare. You generally need both Part A and Part B to join a Medicare Advantage plan. Confirm the choice on Medicare.gov.

• Switch from Original Medicare to a Medicare Advantage plan.
• Switch from Medicare Advantage back to Original Medicare.
• Change from one Medicare Advantage plan to another.
• Join, switch, or drop a stand-alone Part D plan if you have Original Medicare.
• Choose a Medicare Advantage plan with or without drug coverage, if one is sold where you live.

Leaving Advantage is not the same as buying Medigap

If you return to Original Medicare, you may want a separate Part D plan, and you may want a Medicare Supplement. There are limits on when you can buy Medigap without health questions. California’s Birthday Rule is for people who already have a Supplement. It is not the path for leaving Advantage. See Can I switch from Medicare Advantage to Medigap?.

What to compare before you choose

A plan that fit in 2026 can still be the right one. The way to know is to compare the 2027 details against the care you already use. Start with the Annual Notice of Change and mark anything that touches medications, doctors, hospitals, dental or vision, referrals, or the monthly premium.

• Prescriptions: whether each drug is covered, which tier it is on, and whether prior authorization, quantity limits, or step therapy apply.
• Pharmacy: the same drug can cost a different amount at a preferred pharmacy than at another one.
• Doctors and hospitals: for Medicare Advantage, confirm the primary doctor, specialists, and hospital for 2027. “We take Medicare” is not a network answer.
• Yearly cost: premium, deductible, copays, coinsurance, drug costs, and the Medicare Advantage out-of-pocket maximum.
• Extras: dental, vision, hearing, rides, fitness, and over-the-counter allowances. They do not replace the doctors and drugs you need.
• Travel: if you spend time in more than one state, ask how the plan treats non-emergency care outside the service area.

Original Medicare, Advantage, and Part D

Original Medicare is Part A and Part B, run by the federal government. Many people add a stand-alone Part D plan and, if they can buy one, a Medigap policy. Medicare Advantage (Part C) is another way to get Part A and Part B through a private plan Medicare approves. Those plans usually have networks and may include drugs and extras. The details depend on the plan and the county. Part D is the drug coverage, either as its own plan or inside many Advantage plans. Drug lists change, so Part D needs a fresh look every year. The published 2027 Part D numbers are in Medicare changes for 2027 and Medicare Part D in 2027.

A checklist before December 7

Use this even if you expect to keep the current plan. The Annual Enrollment checklist is the same list in a form you can fill in.

• Gather your Medicare card, plan card, and any notices.
• List prescriptions, including the dose and how often you take each one.
• List doctors, specialists, hospitals, and the pharmacy you use.
• Read the Annual Notice of Change for 2027 updates.
• Compare more than one plan in your ZIP code. Medicare Plan Compare is the official list.
• Check that medications and providers are still covered.
• Estimate the year, not only the premium.
• Ask whether extra benefits have dollar limits, networks, or reimbursement rules.
• If you make a change, save the confirmation number and the plan documents.

Mistakes that cost the year

Doing nothing does not freeze 2026. If you stay enrolled, the plan can still change costs and benefits on January 1. Choosing only by the premium is the other common miss: a low premium can cost more if a drug moves tiers or a doctor leaves the network. The third miss is treating January through March as a full do-over. That Medicare Advantage window allows one change, and only if you are already in an Advantage plan.

What national 2027 updates do not decide

CMS has published 2027 Medicare Advantage and Part D policy updates, including changes to quality measures, Star Ratings, and some enrollment processes, plus state landscape files. Those describe the market. They do not tell you whether a plan in your ZIP covers your doctor or your drugs. Star Ratings are one comparison point. A high rating does not replace a formulary or a network check. Official sources are Medicare.gov, the Medicare & You handbook, and 1-800-MEDICARE (1-800-633-4227, TTY 711).