Medicare Open Enrollment runs October 15 through December 7, 2026, for coverage that starts January 1, 2027. That is the plan-choice deadline. IRMAA runs on a different clock, and confusing the two can get expensive. The planner below turns four quick answers into your own Dec. 7 coverage checklist, 2027 IRMAA check, and Dec. 31 income watchlist that you can print or save as a PDF. Medicare confirms the October 15–December 7 Open Enrollment window here.
Many people assume that once they pick a plan, the Medicare-cost decision is finished. It is not.
Here is the bottom line: Open Enrollment lets you choose or change your Medicare Advantage or Part D coverage. It does not determine whether you owe IRMAA. Your total Medicare cost can include both your plan premium and separate income-related surcharges.
For 2027 IRMAA, Social Security will generally look to your 2025 MAGI, because IRMAA normally uses tax information from two years before the premium year. That income year is already closed. What you can still control before December 31, 2026 is your 2026 MAGI, which will generally be used for 2028 IRMAA. See the current IRMAA income brackets, learn how Part B and IRMAA work together, and use the IRMAA planning checklist for year-end moves.
A low-premium plan can still be expensive overall if IRMAA applies. Before you get buried in plan details, use the two-deadline planner below to identify what actually deserves your attention. Then use the deeper checklist and examples to finish the job.
⚡ The Two-Deadline Strategy
- Deadline 1 (Dec 7, 2026): Make your Medicare Advantage or Part D choice for coverage beginning in 2027.
- Deadline 2 (Dec 31, 2026): Finalize year-end income decisions that affect your 2026 MAGI and, generally, your 2028 IRMAA.
- The “Base + Surcharge” Rule: Your total Medicare cost can include the applicable Part B premium, your plan premium, and any Part B or Part D IRMAA you owe.
- The Action: Run the personalized planner next. It separates your Dec. 7 plan-shopping job from your Dec. 31 income-planning job.
On This Page
Key Takeaways Ahead
Build Your Medicare + IRMAA Two-Deadline Plan
Your two-deadline action plan
Four short questions. One practical checklist for comparing your 2027 Medicare coverage and reviewing 2026 income decisions without confusing the two deadlines.
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Your two-deadline checklist
Think of these as two separate clocks: enrollment changes for 2027 and income decisions in 2026.
Boundaries: No 2027 IRMAA bracket or surcharge is calculated until official figures are published. A plan comparison and an SSA determination may differ from this educational checklist.
The “Base + Surcharge” Medicare Advantage Trap
Many retirees use the Medicare Advantage Plan Finder, sort by “Lowest Premium,” and enroll in a $0 or $15/month plan. They feel like they won.
Then, in January, they get a bill from Medicare for $500+ a month. Why?
Medicare Plan Finder only shows the Base Premium. It does not include your personal IRMAA Surcharge.
- Part B: Pay the applicable Part B premium, plus Part B IRMAA if your income is above the published threshold.
- Part D Surcharge: Added to whatever drug plan you choose.
🧮 Your Real Medicare Cost
Do not judge a Medicare plan by the advertised plan premium alone. Your monthly cost can include:
- Part B premium
- Part B IRMAA, if your income is above the applicable threshold
- Medicare Advantage or Part D plan premium
- Part D IRMAA, if applicable
2027 update: The 2027 Medicare handbook still quotes 2026 income thresholds; official 2027 Part B and Part D IRMAA thresholds and surcharges remain pending. Do not carry the 2026 premium or thresholds into 2027. Medicare still directs readers to Medicare.gov for the latest Part B premium amount and income limits, so do not carry the 2026 Part B premium forward as a 2027 number.
💡 Stop overpaying for retirement.
One clear financial move each week — straight from 28 years of seeing what goes wrong.
- → Avoid hidden fees like IRMAA
- → Lower your taxes legally
- → Protect your nest egg
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The 2027 Coverage AEP & IRMAA Master Checklist
Use this timeline to ensure you don’t miss a critical window.
| Dates | Action Item | Why It Matters |
|---|---|---|
| Oct 1 – Oct 15 | Review ANOC and plan changes | Check your 2027 plan changes, including doctors, pharmacies, covered drugs, formularies, and costs before Open Enrollment. |
| Oct 15 – Dec 7 | Compare Plans | Compare and choose coverage for 2027. Check the full annual cost, not just the advertised premium. |
| Nov 15 – Dec 31 | Project 2026 MAGI | Estimate your 2026 IRMAA MAGI. It will generally be the income year used for 2028 Medicare IRMAA. |
| Before Dec 31 | Execute “Income Defense” | Harvest losses, do QCDs, or defer income to stay under an IRMAA cliff. |
Case Study: The “December Surprise”
Here is a simple hypothetical showing why year-end income monitoring matters.
The Setup:
- Date: December 6th.
- Action: Jim and Sarah enroll in a new Part D plan with a $40/month premium. They are happy.
- Income Status: Their projected 2026 MAGI is close to a future IRMAA threshold. The exact 2028 thresholds are not known yet, so they leave themselves a buffer instead of planning to an unpublished number.
The Failure:
- Date: December 20th.
- Event: Their mutual fund pays out a large year-end capital gain distribution of $5,000.
- Result: Their 2026 MAGI rises by $5,000 after they thought their year-end planning was finished.
The Consequence:
Because they stopped watching income after Open Enrollment, they may have increased their 2028 IRMAA exposure. The actual result will depend on the 2028 thresholds and their final tax return.
- What changed: Their MAGI increased after their Medicare plan decision was already finished.
- What to do: Recheck taxable distributions, realized gains, Roth conversions, and other year-end income before December 31.
- What not to do: Do not assume a specific future IRMAA threshold before CMS publishes it.
The Lesson: Open Enrollment ends December 7, but your ability to change most items that affect this year’s MAGI generally ends December 31. Keep monitoring income after you choose your plan. Use the IRMAA Calculator to model current published surcharges, and see the IRMAA appeal and life-changing-event guide if your income has dropped for a qualifying reason.
Defensive Move: The “December Distribution Watchlist”
Action Step: Check your fund provider’s estimated year-end capital gains distributions. If you are near a projected IRMAA threshold, review the tax impact before acting. Selling before a distribution can create its own taxable gain, so compare the consequences rather than selling solely to avoid the distribution.
💡 Stop overpaying for retirement.
One clear financial move each week — straight from 28 years of seeing what goes wrong.
- → Avoid hidden fees like IRMAA
- → Lower your taxes legally
- → Protect your nest egg
📬 No spam. Unsubscribe.
Frequent Reader Questions About AEP & IRMAA
📚 Deepen Your IRMAA Defense
Don’t let surcharges eat your retirement. Check out these guides:
- Capital Gains Spiking Your IRMAA? Use Tax-Loss Harvesting – How year-end gains and losses can affect MAGI.
- IRMAA Appeal Guide (Form SSA-44) – What to investigate after a qualifying life-changing event lowers household income.
Does changing my plan affect my IRMAA?
No. Changing your insurance carrier does not by itself change your IRMAA tier. IRMAA is based on the income information Social Security uses. Your total Medicare cost can still change because plan premiums and IRMAA are separate pieces.
If I retire this year, will I still pay IRMAA?
Possibly. Social Security normally uses tax information from two years earlier, but retirement can be a qualifying life-changing event. If your household income dropped, you can ask Social Security to use more recent information through the SSA-44 process.
Can I pay my IRMAA directly to the plan?
No. IRMAA is paid to Medicare, usually through your Social Security or Railroad Retirement benefit or a Medicare bill. It is separate from the premium you pay your Medicare Advantage or Part D plan.
What are the IRMAA income thresholds for 2027?
The official 2027 Part B and Part D IRMAA income thresholds and surcharge amounts are still pending. Social Security generally uses 2025 MAGI for the 2027 premium year. Married-filing-separately rules are different. See the official Medicare & You 2027 handbook.
Conclusion: Finish the Drill
Most retirees sprint to the December 7th deadline and then stop. That is a mistake.
