Medicare open enrollment: what you can change by December 7

Key points

• Medicare Open Enrollment for 2027 coverage runs from October 15 to December 7, 2026. A change you make in that window starts on January 1, 2027.
• You can move between Original Medicare and Medicare Advantage, switch Medicare Advantage plans, and join, switch or drop a Medicare drug plan.
• If you do nothing, your current plan generally continues into 2027, including any changes to its costs and benefits that it announced in its Annual Notice of Change.
• Open Enrollment is not the window to sign up for Part B, and it gives you no federal right to buy a Medigap policy.

Open Enrollment is the one time each year when almost everyone with Medicare can change how they get their coverage. The window is the same every year, October 15 to December 7, because federal regulations set it that way. This guide covers the federal rules and what to check before the deadline. It is part of our Medicare guide, which covers what Medicare costs and how the income surcharge works.

We do not recommend plans, insurers or agents. The plan that suits one person can be wrong for the next, because it depends on your drugs, your doctors and your budget. What we can do is lay out the rules, so you know what you are choosing between.

When is Medicare open enrollment?

Date	What happens
October 15 to December 7, 2026	Open Enrollment for 2027 coverage
January 1, 2027	Changes made during Open Enrollment start. So do any cost or benefit changes in a plan you kept
January 1 to March 31, 2027	Medicare Advantage Open Enrollment Period: one change, only for people already in a Medicare Advantage plan
January 1 to March 31, 2027	General Enrollment Period for Part B (and Part A if you pay a premium for it), a separate window with its own rules

The plan has to receive your enrollment request by December 7 for the change to start on January 1. You switch to a new drug plan, or a new Medicare Advantage plan with drug coverage, simply by joining it: your old drug coverage ends when the new drug coverage begins.

What can you change during open enrollment?

What you can do depends on what you have now.

If you have now	During Open Enrollment you can
Original Medicare, no drug plan	Join a Medicare drug plan, or switch to a Medicare Advantage plan
Original Medicare and a drug plan	Switch to a different drug plan, drop drug coverage, or switch to a Medicare Advantage plan
A Medicare Advantage plan	Switch to another Medicare Advantage plan, with or without drug coverage, add or drop drug coverage, or return to Original Medicare and join a separate drug plan

Two eligibility rules sit underneath this table. A Medicare Advantage plan requires both Part A and Part B. A stand-alone drug plan requires Part A or Part B.

Moving back to Original Medicare has two consequences. You may need to join a separate drug plan. And if you want a Medigap policy to cover Original Medicare’s gaps, there are limits on when you can buy one (more on that below).

What happens if you do nothing?

People who want to keep their current coverage generally do not need to re-enroll. Your plan simply continues. But it continues on its 2027 terms, not its 2026 terms.

Each year, Medicare Advantage plans can change their coverage, costs and service area, and some leave Medicare entirely. Your plan has to tell you in advance:

• Annual Notice of Change. Lists the changes in coverage and costs that take effect in January. Your plan sends it by September 30.
• Evidence of Coverage. Describes what the plan covers and what you pay in detail. Your plan sends a notice or a printed copy by October 15.

If your plan is leaving Medicare or your area, you get a Special Enrollment Period to choose other coverage.

Doing nothing is a choice like any other. The risk is a change you did not notice: a drug that left the plan’s list, a pharmacy or doctor that left the network, or a higher premium or deductible.

What is already known about 2027?

Some 2027 figures are official. Others were not published when we checked on November 4, 2026.

Item	2026	2027
Most a Part D plan’s deductible can be	$615	$700
Cap on your out-of-pocket costs for covered drugs	$2,100	$2,400
National base beneficiary premium (used for the Part D late penalty)	$38.99	$41.33
Standard Part B premium	$202.90 a month	Not published as of November 4, 2026
Part B deductible	$283	Not published as of November 4, 2026

CMS also projected averages for 2027. The average monthly premium for stand-alone drug plans was projected to rise from $35.09 to $36, and the weighted average Medicare Advantage premium to fall from $14.37 to $12.00. Those are averages across every plan. Your own plan’s premium is in its Annual Notice of Change and in the Plan Finder.

CMS had not published the 2027 Part B premium, deductible or income brackets when we checked on November 4, 2026. Our guide to the Part B premium covers the 2026 amounts and will carry 2027’s when they are out. Drug costs have their own guide: what Medicare Part D costs.

How to review your coverage before December 7

Six steps, in order. None of them requires an agent.

1. Read the Annual Notice of Change. Check the premium, the deductible, whether each of your drugs is still on the plan’s drug list, and whether your doctors and pharmacy are still in the network.
2. Write down your drugs, doses and pharmacies. You will need this list to compare drug costs between plans.
3. Compare plans in the Medicare Plan Finder at https://www.medicare.gov/plan-compare. It compares health and drug plans, including premiums, costs and benefits.
4. Check other coverage first. If you have coverage from an employer, a union or a former employer, joining a Medicare Advantage plan or adding Medicare drug coverage can end that coverage for you and your family, and you may not be able to get it back. Ask the benefits office before you change anything. Our guide on Medicare when you still have employer insurance explains how the two fit together.
5. If you have Medigap now, treat leaving it as hard to undo. Most Medigap policies do not cancel automatically when you join a Medicare Advantage plan (cancelling is a separate step with the insurer), and Medigap cannot pay a Medicare Advantage plan’s costs. If you later go back to Original Medicare, you may not get the same policy back, and outside a few protected situations an insurer can refuse to sell you one or charge more because of your health.
6. Make the change by December 7. You can join a plan through the Plan Finder, through the plan, or by calling 1-800-MEDICARE (1-800-633-4227, TTY 1-877-486-2048).

Plans must follow marketing rules. A plan does not need your personal information to give you a quote, and it cannot sign you up over the phone unless you called it and asked to sign up, or gave it permission to contact you. Medicare asks you to report, at 1-800-MEDICARE, any plan or agent that asks for personal information by phone or email, calls to enroll you, or visits you unexpectedly.

Dropping or skipping a drug plan: the late penalty

Open Enrollment is also when people drop a drug plan they rarely use. That can be expensive later.

If, after your Initial Enrollment Period, you go 63 days or more in a row without Part D or other creditable drug coverage, a late enrollment penalty can apply when you join a plan later. Creditable coverage means drug coverage expected to pay, on average, at least as much as standard Part D, for example from a current or former employer or union, TRICARE, the VA or the Indian Health Service. Your plan has to tell you each year whether its drug coverage is creditable.

The penalty is 1% of the national base beneficiary premium for each full month you went without coverage, rounded to the nearest $0.10 and generally added to your premium for as long as you have Part D. It is recalculated each year with the new base premium, so the dollar amount can rise or fall. People who get Extra Help do not pay it.

Worked example (hypothetical). Someone’s Initial Enrollment Period ended on March 31, 2025. They had no Part D and no other creditable drug coverage after that. They join a drug plan during this Open Enrollment, so coverage starts January 1, 2027.

• Uncovered months: April 2025 through December 2026, which is 21 months, so a 21% penalty.
• 21 x 1% x $41.33 = $8.68, rounded to the nearest $0.10 = $8.70 a month on top of the plan’s premium in 2027.
• That is $104.40 over 2027, and the penalty continues in later years, recalculated with each year’s base premium.
• Waiting one more Open Enrollment would mean 33 uncovered months: a 33% penalty, or $13.60 a month at the 2027 base premium.

We checked the method against Medicare’s own example in the 2027 handbook: 29 uncovered months times the 2025 base premium of $36.78 is $10.67, paid as $10.70, and recalculated with the 2026 base of $38.99 it is $11.31, paid as $11.30. Our script reproduces both. If you get a penalty letter and think it is wrong, you can ask for a reconsideration within 60 days of the date on the letter, and you keep paying while it is reviewed. The full rules for both Part B and Part D penalties are in our guide to the Medicare late enrollment penalty.

What open enrollment does not do

It does not sign you up for Part B. After your Initial Enrollment Period, Part B can only be added in the General Enrollment Period (January 1 to March 31, with coverage starting the month after you sign up) or in a Special Enrollment Period, for example after employer coverage from current work ends. Open Enrollment is for choosing health and drug plans. Our guide on when to apply for Medicare covers every sign-up window.

It does not give you a right to buy Medigap. Your federal Medigap Open Enrollment Period is the 6 months that start the first month you have Part B and are 65 or older. Outside that window, and outside the situations where Medicare says you have “guaranteed issue rights,” federal law does not require an insurer to sell you a policy, and if one does, it may cost more because of past or present health problems. Some states give more rights than federal law. The trade-offs are in our guide to Medigap vs Medicare Advantage.

Missed December 7? Your options after open enrollment

You may still have a way to change, depending on your situation.

• Medicare Advantage Open Enrollment Period, January 1 to March 31. If you are in a Medicare Advantage plan, you can make one change: switch to another Medicare Advantage plan, or return to Original Medicare and join a drug plan. The change starts the first of the month after the plan gets your request. If you go back to Original Medicare and join a drug plan, you are disenrolled from the Medicare Advantage plan automatically. This window cannot be used to move from Original Medicare into Medicare Advantage, or to join or switch a drug plan while you are in Original Medicare.
• New to Medicare Advantage. If you joined a Medicare Advantage plan during your Initial Enrollment Period, you can switch plans or go back to Original Medicare within the first 3 months you have Medicare.
• Trying Medicare Advantage at 65. If you joined a Medicare Advantage plan when you were first eligible at 65, you can return to Original Medicare within 12 months of joining, with special rights to buy a Medigap policy for a limited time.
• A 5-star plan. If a plan rated 5 stars is available where you live, you can switch to it once between December 8 and November 30 of the following year.
• Medicaid or Extra Help. You can change your drug coverage once a calendar month, effective the first day of the next month.
• Life events. Moving, losing other coverage and some other changes open a Special Enrollment Period. Outside these, someone who joins a Medicare Advantage plan generally keeps it for the calendar year.

Where to get free help

State Health Insurance Assistance Programs (SHIPs) give free, personalized Medicare counseling, and they are not connected to any insurance company or plan. Find yours at shiphelp.org or through 1-800-MEDICARE. 1-800-MEDICARE (1-800-633-4227, TTY 1-877-486-2048) is open 24 hours a day, 7 days a week, and you can switch plans through it.

For what Medicare costs once you add premiums, deductibles and drugs together, see how much Medicare costs.

About this guide

Written by the Diversify Guy editorial desk. Diversify Guy is a pen name. It is the byline of our editorial team, not a single individual. We do not publish personal trading records or claim to be your adviser. We tell you where every figure came from so you can check it yourself. How we work and how we get paid.

This guide explains federal Medicare rules; some states add their own rules for Medigap and other coverage. It is not personalized insurance, tax, legal or financial advice. Diversify Guy earns affiliate commissions and advertising fees from companies featured elsewhere on the site. This page carries no ads and no affiliate links.

Sources and check dates

All sources checked on November 4, 2026.

• Medicare & You 2027, the official handbook (Open Enrollment dates, plan notices, Medicare Advantage Open Enrollment Period, Medigap timing, the Part D late penalty and its worked example, 2027 Part D deductible and cap, marketing rules, SHIP): https://www.medicare.gov/publications/10050-medicare-and-you.pdf
• Medicare.gov, Open Enrollment: https://www.medicare.gov/health-drug-plans/open-enrollment
• Medicare.gov, joining a plan: https://www.medicare.gov/basics/get-started-with-medicare/get-more-coverage/joining-a-plan
• Medicare.gov, Special Enrollment Periods: https://www.medicare.gov/basics/get-started-with-medicare/get-more-coverage/joining-a-plan/special-enrollment-periods
• Medicare.gov, switch, drop or rejoin a drug plan: https://www.medicare.gov/health-drug-plans/part-d/basics/choose-coverage/switch-drop-rejoin
• Medicare.gov, when Medicare coverage starts: https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-does-medicare-coverage-start
• Medicare.gov, when you can buy Medigap: https://www.medicare.gov/health-drug-plans/medigap/ready-to-buy/when
• Medicare.gov, avoid late enrollment penalties: https://www.medicare.gov/basics/costs/medicare-costs/avoid-penalties
• Medicare.gov, How Medicare works with other insurance (publication 02179): https://www.medicare.gov/publications/02179-how-medicare-works-with-other-insurance.pdf
• CMS press release on 2027 Medicare Advantage and Part D premiums and Open Enrollment: https://www.cms.gov/newsroom/press-releases/medicare-advantage-medicare-prescription-drug-programs-expected-remain-stable-2027
• CMS, Part D 2027 national average monthly bid amount and base beneficiary premium: https://www.cms.gov/newsroom/fact-sheets/medicare-part-d-2027-national-average-monthly-bid-amount-information
• CMS, 2026 Part D bid information and base beneficiary premium: https://www.cms.gov/newsroom/fact-sheets/2026-medicare-part-d-bid-information-and-part-d-premium-stabilization-demonstration-parameters
• CMS, CY 2027 Rate Announcement (Part D deductible and out-of-pocket threshold): https://www.cms.gov/files/document/2027-announcement.pdf
• CMS, 2026 Medicare Parts A and B premiums and deductibles fact sheet: https://www.cms.gov/newsroom/fact-sheets/2026-medicare-parts-b-premiums-deductibles
• CMS address for the 2027 Part B fact sheet, which returned “Page Not Found” on November 4, 2026: https://www.cms.gov/newsroom/fact-sheets/2027-medicare-parts-b-premiums-deductibles
• 42 CFR 422.62 and 422.68 (Medicare Advantage election periods and effective dates): https://www.ecfr.gov/current/title-42/section-422.62 and https://www.ecfr.gov/current/title-42/section-422.68
• 42 CFR 423.38, 423.46, 423.56 and 423.286 (Part D enrollment periods, late penalty, creditable coverage): https://www.ecfr.gov/current/title-42/section-423.38, https://www.ecfr.gov/current/title-42/section-423.46, https://www.ecfr.gov/current/title-42/section-423.56 and https://www.ecfr.gov/current/title-42/section-423.286
• 42 CFR 407.15 and 407.25 (Part B General Enrollment Period and coverage start): https://www.ecfr.gov/current/title-42/section-407.15 and https://www.ecfr.gov/current/title-42/section-407.25
• 42 CFR 406.24 and 407.20 (the Special Enrollment Period based on current employment): https://www.ecfr.gov/current/title-42/section-406.24 and https://www.ecfr.gov/current/title-42/section-407.20
• Medicare.gov, working past 65: https://www.medicare.gov/basics/get-started-with-medicare/medicare-basics/working-past-65