Medicare Enrollment: When to Sign Up and What Open Enrollment Lets You Change

Medicare Enrollment: When to Sign Up, and What You Can Change Each Fall

Key takeaways

• Your first chance to sign up is a 7-month window around your 65th birthday.[1]
• Miss it, and you may pay a Part B late penalty for as long as you have Part B.[1]
• Open Enrollment runs October 15 to December 7 every year. Changes start January 1.[2]
• Still working with job insurance? You may get an 8-month window after the job or coverage ends.[1][3]
• A SHIP counselor gives free, unbiased help. SHIPs are not tied to any insurance company.[2][4]

Step 1: Your first window (Initial Enrollment Period)

It lasts 7 months. It starts 3 months before the month you turn 65. It ends 3 months after that month.[1]

When coverage starts:[1]

Premium-free Part A starts the month you turn 65.[1]

Tip: Sign up early in the window. Then there is no gap.

Step 2: Do you need to sign up now?

Many people already getting Social Security are enrolled automatically. Others sign up through Social Security (SSA.gov).[1][5]

Answer these questions:

• Do I (or my spouse) have health insurance from a current job?
• How many employees does that employer have? Medicare asks if it is 20 or more.[3]
• Do I have COBRA or retiree coverage? These do not give you a later window.[1]
• Do I have an HSA? Ask your employer before signing up.[3]
• Do I have Marketplace coverage? You may lose help paying premiums once you can get Part A.[3]

If you or your spouse are still working with job coverage, you can often delay Part B. You then get an 8-month Special Enrollment Period after the job or coverage ends — whichever comes first.[1][3] COBRA does not extend it.[1]

Step 3: Every fall — Open Enrollment (Oct 15 – Dec 7)

During this window you can:[2]

• Switch from Original Medicare to a Medicare Advantage Plan, or back.
• Join, switch, or drop a Medicare Advantage Plan.
• Join, switch, or drop a Part D drug plan.

The plan must get your request by December 7. New coverage starts January 1.[2]

Do this every fall (original checklist):

1. Read your plan's "Annual Notice of Change" letter.
2. List every drug you take, with the dose.
3. List your doctors and pharmacy.
4. Compare plans at Medicare.gov/plan-compare. Enter all your drugs.[2]
5. Ask each doctor: "Are you in this plan's network next year?"[2]
6. Not sure? Call your SHIP before December 7.

Other windows to know

Watch out for scams

Medicare will not call you to sell a plan. Learn the warning signs on our Medicare scams page. You can also try

.

Where to get free help

• SHIP: free, local, one-on-one counseling. Find yours at shiphelp.org. [4]
• Medicare: 1-800-MEDICARE (1-800-633-4227). TTY 1-877-486-2048.[2]
• Social Security: SSA.gov for Part A/B sign-up.[5]
• Limited income? See Medicaid eligibility.
• Not sure what help you qualify for? Try our

.

Learn step by step:

• Related: Medicare Part D drug coverage
• Related: Medicare Advantage vs. Medigap

Sources

1. Centers for Medicare & Medicaid Services. When does Medicare coverage start? Medicare.gov. https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-does-medicare-coverage-start. Accessed October 29, 2026.
2. Centers for Medicare & Medicaid Services. Joining a plan. Medicare.gov. https://www.medicare.gov/basics/get-started-with-medicare/get-more-coverage/joining-a-plan. Accessed October 29, 2026.
3. Centers for Medicare & Medicaid Services. When can I sign up for Medicare? Medicare.gov. https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-can-i-sign-up-for-medicare. Accessed October 29, 2026.
4. SHIP National Technical Assistance Center. Get Medicare help from your local SHIP. https://www.shiphelp.org/. Accessed October 29, 2026.
5. Social Security Administration. Apply for Medicare. https://www.ssa.gov/medicare. (Referenced via Medicare.gov sign-up pages; not separately opened — reviewer to confirm URL.)

Disclaimer

This article is for general education only and is not medical, legal, or financial advice. We do not sell, endorse, or recommend any insurance plan or company. Talk to your doctor, a licensed attorney, or a SHIP counselor (Medicare) about your situation. In an emergency, call 911.

Attribution

Portions of this page are adapted from "HowToLiveBetter" (高性价比人生指南) by eternity4719, https://github.com/eternity4719/HowToLiveBetter, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Changes: adapted and rewritten for the U.S. context (not a direct translation), and re-sourced to U.S. official guidance. The source chapter on China's health insurance (ch. 24) was not used; all Medicare content is written from scratch.