Your 2027 Medicare Open Enrollment Guide: Essential Dates and Notices

Medicare beneficiaries can expect some important mail beginning in September. The official Medicare notices, plan updates and statements you receive play a critical role in guiding your healthcare decisions. Far from routine “junk mail,” these official notices serve as a personal roadmap to evaluate your care and protect your wallet.

Each year, the Medicare open enrollment Period (also known as the annual election period (AEP)) runs from October 15 to December 7. During this window, you have the opportunity to review your healthcare and prescription coverage, compare it against new plans available in your area and make any necessary changes for the upcoming coverage year starting January 1.

Open enrollment calendar

Medicare beneficiaries should be careful to take note of the dates below. Some are hard and fast deadlines and others will alert you to days when important information is being released or should arrive in your mailbox.

Some of this information will be accessible earlier if you have (or create) a my Social Security account and/or Medicare account.

Notices you need to watch for

Medicare’s annual open enrollment period runs every year from October 15 through December 7. This limited, seven-week window is your primary opportunity to review your current health and drug plans, compare new options available in your area and adjust your coverage for the coming calendar year.

Navigating these choices can feel overwhelming, but you don’t have to guess what is changing. The official Medicare notices, plan updates and statements you receive in the mail play a critical role in guiding your decisions during open enrollment.

Here is how keeping a close eye on these specific pieces of mail empowers you to make informed decisions before the December 7 deadline:

• Spotting changes before they take effect
  • The Annual Notice of Change (ANOC) should arrive by September 30 and serves as your early-warning system. It outlines exact changes your Medicare Advantage plan is making for the coming year — such as higher copays, dropped doctors or hospitals, and removed medications. Reading it tells you whether your plan is still a good fit or if it’s time to switch.
• Avoiding unexpected gaps or loss of coverage
  • Notices like the Plan Non-Renewal or Termination Notice alert you if your insurer is pulling out of your county or discontinuing your plan entirely. Receiving a plan non-renewal notice in the fall ensures you aren’t caught off guard on January 1 without coverage. A termination notice can come at any time and unlocks a special enrollment period (SEP) so you can select a replacement plan.
• Managing prescription drug costs
  • Mid-year formulary notices and ANOC updates highlight upcoming shifts in drug coverage tiers, brand-to-generic substitutions or new prior authorization requirements. Armed with this information, you can compare prescription drug plans (Part D) on Medicare.gov during open enrollment to find a plan that covers your specific medications at the lowest out-of-pocket cost.
• Planning your personal health care budget
  • IRMAA Determination letters and Social Security COLA statements detail your exact monthly Part B/D premium costs, income surcharges and net benefits for the coming year. Knowing these fixed costs helps you determine how much room you have in your budget for plan copays, coinsurance, or private Medicare Advantage premiums/supplemental insurance.
• Protecting against errors and fraud
  • Reviewing your 2026 Medicare Summary Notices (MSN) or explanation of benefits (EOB) helps you verify what services you used throughout the past year, track progress toward deductibles and ensure you aren’t paying for services you never received before you reevaluate your coverage needs.

Don’t ignore the notices or deadlines

As the December 7 open enrollment deadline approaches, taking a few minutes to review the notices in your mailbox can make a significant difference in both your healthcare coverage and your wallet for the year ahead. If you sign up for a my Social Security or Medicare account, you can receive the notices earlier via email.

Rather than leaving these mailings or emails unopened, use them to verify that your doctors stay in-network, your prescriptions remain covered and your out-of-pocket costs fit your financial plan. If your current coverage no longer works, open enrollment lets you switch to a better plan — ensuring seamless care and peace of mind on January 1.

Related Cotent

• 8 Changes Coming to Medicare in 2027
• Don’t Toss It! Why Your Medicare Annual Notice of Change Matters
• The 7-Month Deadline That Determines Your Lifetime Medicare Premiums
• Medicare 2027 Projections: Here’s How Much Your Monthly Premiums Are Estimated to Rise