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What Happens If I Miss Medicare Open Enrollment?

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If you miss Medicare Open Enrollment on December 7, 2026, one thing is certain: you keep the plan you have for all of 2027. The good news is that for most people that is the whole cost. The bad news is that two situations turn a missed date into a bill you pay every month for the rest of your life. This page tells you which side you’re on and how to get back in.

Timeline from October 2026 to April 2027 showing the Open Enrollment window October 15 to December 7, the locked period through December 31, the new-plan start on January 1, and the January 1 to March 31 Medicare Advantage window
Two windows, not one. The second is only for people already in a Medicare Advantage plan.

What actually happens, by situation

On December 8, 2026 I have…What happensWay back in
A Medicare Advantage planIt renews for 2027 with its new pricesOne switch January 1 – March 31, 2027
Original Medicare + a Part D drug planBoth continue; the drug plan’s 2027 premium and formulary applySpecial enrollment period only, else October 15, 2027
Original Medicare + a Medigap policyNothing changes; Medigap has no annual windowApply any time (health questions may apply)
Part B but no drug coverage for 63+ daysPart D penalty starts buildingJoin a drug plan in any window you qualify for; the penalty stays
No Part B and no employer coveragePart B penalty builds for each 12 monthsGeneral Enrollment January 1 – March 31, coverage the next month

Windows from Medicare.gov’s enrollment periods page.

The two penalties, in plain numbers

Part B. If you could have had Part B but didn’t sign up and had no employer coverage, your premium goes up 10% for each full 12-month period you waited, and the increase never comes off (Medicare.gov). On the 2026 standard premium of $202.90 (CMS), two years late means roughly $40 more every month, for life.

Part D. Go 63 days without creditable drug coverage and Medicare adds 1% of the national base premium for every month you were uncovered, for as long as you have drug coverage (Medicare.gov). Twenty uncovered months means a 20% surcharge on that base amount every month.

Neither penalty is triggered by missing October 15 – December 7. They are triggered by having nothing. If you already have Part B and a drug plan (or an Advantage plan with drugs), missing the deadline costs you only the chance to shop.

Already missed it? Three doors that are still open

1. The January window (Advantage members only). Between January 1 and March 31 you can switch to another Advantage plan once, or drop Advantage and return to Original Medicare plus a drug plan. Coverage starts the month after you switch.

2. A special enrollment period. Certain life events open a window any month. The common ones: you moved out of your plan’s service area, you lost employer or union coverage, your plan is leaving Medicare, you qualified for Extra Help or Medicaid, or you moved into or out of a nursing home. Most give you about two months. Call 1-800-MEDICARE (1-800-633-4227) with the date of the event.

3. Still working with employer coverage? You are not late. When that coverage ends, you get 8 months to sign up for Part B with no penalty (Medicare.gov). Mark the end date the day you retire.

Before December 7: a 10-minute check

  • Read the Annual Notice of Change your plan mailed in September. Premium, deductible and drug list for 2027 are in it.
  • Put your drugs into the Medicare Plan Finder. It shows your real 2027 cost per plan, pharmacy included.
  • Confirm your doctors are still in the network for 2027. Networks change every year.
  • If anything got worse, switch before December 7. The new plan starts January 1.
  • Free one-on-one help: your State Health Insurance Assistance Program (SHIP), listed at shiphelp.org.

One thing to do today

Find your row in the table above. If you’re in the “no Part B” or “no drug coverage” rows, the clock is already running; call 1-800-MEDICARE this week. Everyone else: put December 7 on the calendar and do the 10-minute check before then.

We update this page the day CMS announces the 2027 Part B premium. Next: the 2026 Part B premium and IRMAA brackets and the Open Enrollment checklist.

Questions people ask about this

Is there a penalty for missing Medicare open enrollment?

Not for missing October 15 to December 7 itself. You simply keep your current plan for 2027. Penalties only apply if you have no Part B or no creditable drug coverage.

Can I still change my plan after December 7?

If you are in a Medicare Advantage plan on January 1, yes: one switch between January 1 and March 31, 2027. If you are in Original Medicare, only a special enrollment period lets you change before October 15, 2027.

What counts as a special enrollment period?

Moving out of your plan's area, losing employer or Medicaid coverage, your plan leaving Medicare, qualifying for Extra Help, or moving into or out of a nursing home. Each has its own window, usually two months.

I never signed up for Part D. What does that cost?

1% of the national base premium for every full month without creditable drug coverage, added to your premium for as long as you have Medicare drug coverage. Sixty-three days without coverage starts the clock.

I'm still working at 65. Do I have to enroll?

If you have employer coverage from a large employer, you can wait. You then get 8 months after that coverage ends to sign up for Part B without a penalty.

Sources

  1. Medicare.gov: Joining a plan (enrollment periods)
    www.medicare.gov
  2. Medicare.gov: Avoid late enrollment penalties (Part B)
    www.medicare.gov
  3. Medicare.gov: Part D late enrollment penalty
    www.medicare.gov
  4. Medicare.gov: When does Medicare coverage start (special enrollment after job coverage)
    www.medicare.gov
  5. Medicare.gov: Plan Finder
    www.medicare.gov
  6. CMS: 2026 Medicare Parts A and B premiums and deductibles
    www.cms.gov
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Benefit Calendar Editors

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