Your fall calendar, in one place
Key Medicare & Social Security dates for fall 2026 into 2027
Every autumn, two of the biggest numbers in your year land almost on top of each other. You learn your Social Security cost-of-living raise, and — at the very same time — you get the window to change your Medicare plan. This page lays out the whole overlap, in order, so nothing sneaks up on you.
The season at a glance
Two announcements, one busy autumn.
The dates below run from midsummer, when the first 2027 COLA estimates appear, through the following spring, when the last enrollment window closes. The two you can act on are the Annual Enrollment Period and the Medicare Advantage Open Enrollment Period — everything else is a heads-up so you're ready.
Want the short version? The official COLA arrives October 14, 2026, and Medicare Open Enrollment runs October 15 – December 7, 2026.
- Mid-July 2026 Early 2027 COLA projections begin. Groups like AARP and The Senior Citizens League publish estimates as summer inflation data comes in. The current early estimate is 3.6% — a projection, not the official figure.
- September 2026 CMS releases the Medicare Landscape and Crosswalk files, and your plan mails you its Annual Notice of Change (ANOC) — the booklet that spells out how your plan's costs and benefits move next year. Read it, don't file it away.
- October 14, 2026, 8:30 a.m. ET The Bureau of Labor Statistics releases September CPI-W inflation data, and the Social Security Administration announces the official 2027 COLA. This is the day the estimate becomes real.
- October 15 – December 7, 2026 Medicare Annual Enrollment Period (AEP). This is the main window to compare, switch, or change your Medicare Advantage and Part D coverage for 2027. Open to everyone with Medicare.
- Late November 2026 Your personalized COLA notice starts appearing in the message center of your my Social Security account online — usually before the paper version reaches your mailbox.
- December 2026 Mailed COLA notices go out, confirming your new monthly benefit amount and any change to your Part B deduction.
- January 1, 2027 The new plan year and new benefit amounts begin. Your COLA raise shows up in your payment, and any Medicare plan change you made during AEP takes effect.
- January 1 – March 31, 2027 Medicare Advantage Open Enrollment Period (OEP). A second, narrower window — for people already in a Medicare Advantage plan — to make one change if the new year isn't working out.
What you can change during AEP
The Annual Enrollment Period (October 15 – December 7) is the one time every year when almost any Medicare change is on the table. Here's what you're allowed to do:
- Switch between Original Medicare and Medicare Advantage. Move from Original Medicare (Parts A and B) into a Medicare Advantage plan, or leave Medicare Advantage and go back to Original Medicare.
- Change from one Medicare Advantage plan to another. If a different plan in your area fits your doctors, drugs, or budget better next year, you can move to it.
- Add, drop, or switch your Part D drug coverage. Join a stand-alone Part D plan, drop the one you have, or switch to a different one. Comparing drug plans each year matters — nationwide, stand-alone Part D plan choices fell from 474 in 2025 to 367 in 2026.
Any change you make during AEP takes effect January 1, 2027. Your current plan keeps running until then.
AEP and the MA OEP are not the same window
AEP (October 15 – December 7) is open to everyone with Medicare, and you can make as many changes as you like — only your last choice counts. The Medicare Advantage Open Enrollment Period (January 1 – March 31, 2027) is different: it's only for people already enrolled in a Medicare Advantage plan, and it allows just one change — switch to another MA plan, or drop back to Original Medicare (and add a Part D plan). If you're on Original Medicare on January 1, the MA OEP is not for you.
How the two big numbers connect
The reason this calendar feels crowded is that your raise and your plan are decided in the same few weeks. Your COLA depends on inflation measured over the summer; your Medicare choices depend on files CMS publishes in early fall. By the time you're comparing plans in November, you already know your raise — so you can weigh both at once.
Two things decide what actually reaches your bank account: the COLA itself, and your Medicare Part B premium, which is usually withheld straight from your Social Security check. When Part B rises, it quietly claws back part of the raise. That's the gap our COLA calculator is built to show you.
Estimate your 2027 raise
Enter your benefit and we'll apply the COLA, then subtract Part B to show the increase you actually keep. Runs entirely in your browser.
COLA calculator →See what changed in your plan
Pick your plan and compare 2026 to 2027 side by side — premium, deductible, max out-of-pocket, star rating, and dropped extras.
What Changed tool →Frequently asked questions
When will I actually see the bigger check?
The 2027 COLA is announced on October 14, 2026, but the higher amount doesn't arrive right away. The new benefit takes effect for January 2027, which most people receive in their payment in January 2027. You'll get a notice in your my Social Security message center in late November, and a mailed notice in December, confirming your new amount before it starts.
What if I miss the Annual Enrollment Period?
If you miss AEP (October 15 – December 7), your current coverage simply carries into 2027 with whatever changes your plan made — so it's worth reading your ANOC even if you plan to stay put. If you're already in a Medicare Advantage plan, you get one more chance during the MA Open Enrollment Period, January 1 – March 31, 2027, to switch plans or return to Original Medicare. Outside those windows, you generally need a Special Enrollment Period, which is triggered by specific life events like moving. Check your options on the official Medicare Plan Finder or by calling 1-800-MEDICARE.
Is the 3.6% COLA for 2027 final?
No. The 3.6% figure is an early estimate from groups like The Senior Citizens League and AARP, based on inflation data so far. By law, the official COLA is the percentage increase in the average CPI-W for July, August, and September over the same quarter of the last year a COLA took effect, rounded to the nearest tenth. The Social Security Administration announces the official number on October 14, 2026. For comparison, the confirmed 2026 COLA was 2.8%.
Where do these dates come from?
All of them come from public government sources: the Social Security Administration and Bureau of Labor Statistics for the COLA, and CMS for the Medicare enrollment periods and plan files. BenefitDial is independent — we're not a broker or agent, we take no commissions, and we never ask for your name, phone number, or email. We just line the dates up for you.
Get both answers before the season starts.
Bookmark this calendar. When your COLA is announced and Open Enrollment opens, you'll already know what to check and when.