Medicare Open Enrollment 2027: Dates, Deadlines, and What to Check Before December 7

Published September 2026 — the enrollment window opens October 15.

Medicare Open Enrollment is the one window each year when every Medicare beneficiary can change their coverage. It's also the window most people sleep through, then discover in January that a drug moved to a higher tier or their doctor left the network.

Here's how the window works, what's changing for 2027, and a checklist you can work through before December 7.

The Dates That Matter

Two details people get wrong:

• It's a hard deadline with a receipt requirement. Per Medicare.gov, your plan must receive your enrollment request by December 7. Mailing on December 5 is not the same as it arriving.
• The January–March window is narrower. The Medicare Advantage Open Enrollment Period only lets you switch or drop a Medicare Advantage plan. It does not let you start, stop, or change a standalone Part D drug plan.

What You Can Actually Change

During Open Enrollment, your options depend on what you have now:

What's New for 2027

Part D out-of-pocket cap: $2,400. The Inflation Reduction Act's annual cap on prescription drug spending continues to adjust upward. For 2027 the cap is $2,400 — once you reach it, covered formulary drugs cost you nothing for the rest of the year.

The Part D deductible is $700. Some plans charge less; a few charge no deductible at all. This is where comparing plans gets interesting, because a low premium alongside a full deductible can cost more overall than a higher premium with a $0 deductible.

Other 2027 figures worth knowing:

• Insulin remains capped at $35 per month per covered insulin product
• Recommended vaccines are free under Part D
• The base beneficiary premium is $41.33 — though what you pay depends on your plan and income

Reality check: Part B premiums and the Part B deductible for 2027 are typically confirmed by CMS in the fall. Check Medicare.gov for the official figures before comparing total costs.

The 5-Step Checklist

1. Read your Annual Notice of Change

Your plan must send an Annual Notice of Change (ANOC) before the enrollment period. It's dense, but it's the single most valuable document you'll get — it tells you exactly what's changing next year: premiums, deductibles, copays, covered drugs, and network changes.

If you read nothing else, read this.

2. List your drugs — then check the 2027 formulary

Write down every prescription, the dose, and how often you fill it. Then check each one against the 2027 formulary for any plan you're considering. Look at the tier, not just whether the drug is covered. A drug that stays on the formulary but moves from Tier 2 to Tier 4 can cost dramatically more.

Also check for prior authorization and step therapy requirements. A drug can be "covered" and still be practically unavailable without a fight.

3. Check your pharmacies

Most plans have preferred pharmacies where your copays are lower. If your usual pharmacy is out of network for a plan, your costs change even if the drug coverage looks identical. Also compare mail-order pricing — for maintenance medications it's often the cheapest option.

4. Verify your providers are still in network

Networks change every year. Call your doctors and confirm they'll accept the plan in 2027 — and confirm the facilities you use (hospital, imaging, labs) are covered too. A doctor who's in network at a hospital that isn't can still generate out-of-network bills.

5. Compare total annual cost, not the premium

This is where people leave money on the table. Add up:

• Annual premiums
• Deductible
• Copays for your specific drugs across a full year
• Expected out-of-pocket for other care

Then compare. The plan with the lowest monthly premium is frequently not the cheapest plan for your actual prescriptions.

One Warning About Switching to Medicare Advantage

Moving from Original Medicare to Medicare Advantage is easy during Open Enrollment. Moving back is easy too — but replacing a Medigap policy is not.

If you leave Original Medicare and drop a Medigap supplement, getting a new Medigap policy later can require medical underwriting, and Medigap insurers can generally decline you or charge more based on health history. (A handful of states have more generous rules.) Medicare.gov notes there are limits on when you can buy Medigap.

So the switch is not symmetric. If you have Original Medicare with a Medigap policy you're happy with, be very deliberate about giving it up.

Free Help Exists — Use It

You don't have to do this alone:

• 1-800-MEDICARE (1-800-633-4227), 24/7
• Medicare.gov Plan Compare — enter your drugs and pharmacies for a personalized cost estimate
• SHIP (State Health Insurance Assistance Programs) — free, unbiased, one-on-one counseling in every state

Be aware that private brokers are paid by insurers. That doesn't make them useless, but it does mean free, commission-free help is worth knowing about.

Why This Belongs in a Retirement Plan

Healthcare is the largest wildcard expense in retirement, and Medicare premiums are only part of it. Dental, vision, hearing, and long-term care sit largely outside Medicare. Getting the plan choice right saves hundreds per year; getting the funding right is worth far more.

We covered the broader picture in retirement healthcare costs and how to plan. To see how healthcare spending affects your own projection, model it in the retirement calculator or the full planner.

Related reading:

• Retirement healthcare costs: what to expect
• Social Security COLA 2027: what to expect
• How to create a retirement budget

This article is educational and not insurance or medical advice. Plan details, formularies, and costs vary by plan and location — verify everything against your own plan documents and Medicare.gov before enrolling.