Medicare Open Enrollment 2026:
What IRMAA Means for Your Plan Choice

Open Enrollment Is Here: October 15 Through December 7

Medicare's annual open enrollment period runs from October 15 through December 7, 2026. During this window, Medicare beneficiaries can switch Part D prescription drug plans, move between Original Medicare and Medicare Advantage, or make other coverage changes that take effect January 1, 2027.

For most beneficiaries, this is the one time each year to reevaluate whether their current plan still fits. Premiums change, formularies shift, and provider networks evolve. Shopping around during open enrollment is often considered a smart move.

But there is a cost layer that most plan comparison tools do not display, and it can dwarf the premium differences between plans. That cost is IRMAA.

What IRMAA Is Not

The most common misconception during open enrollment season: people assume their Medicare premium is their total cost, and that switching to a lower-premium plan will reduce what they owe each month.

IRMAA, the Income-Related Monthly Adjustment Amount, is not your plan premium. It is a surcharge that SSA adds on top of whatever plan you select. It applies to both Part B and Part D, and it is determined entirely by your income, not by your plan choice.

Switching from a $45/month Part D plan to a $12/month Part D plan saves you $33 per month in premium costs. But if you are in an IRMAA tier, your surcharge remains exactly the same regardless of which plan you choose. You cannot shop your way out of IRMAA.

How IRMAA Affects Part D Plan Shopping

When you compare Part D plans during open enrollment, the premium listed on Medicare.gov or your plan finder tool is the base cost of the plan. If you are subject to an IRMAA surcharge, your actual monthly Part D cost is higher than what the tool displays.

Your real Part D cost each month equals the plan premium plus your Part D IRMAA surcharge. Depending on your income tier, that surcharge ranges from $14.50 to $91.00 per month on top of whatever plan you select.

This does not mean plan shopping is pointless. Choosing a plan with lower premiums, a better formulary match, or preferred pharmacy pricing still matters. The point is that IRMAA adds a fixed layer of cost that no amount of plan optimization can reduce. IRMAA doesn't warn you, it bills you.

The Real Cost of Plan Selection with IRMAA

To see how IRMAA changes the math, the table below combines a sample Part D plan premium with the actual Part B and Part D surcharges at each IRMAA tier. All figures are per person, per month, using 2026 CMS-published rates. The sample plan premium used is $46.50 (the national average).

At the top tier, a beneficiary pays $827.40 per month for Part B and Part D combined. For a couple where both spouses are on Medicare, that figure doubles to $1,654.80 per month, or $19,857.60 per year. The plan premium is a small fraction of the total.

First-Time Enrollees: What to Expect

If you are turning 65 and enrolling in Medicare for the first time during this period, IRMAA may come as an unexpected addition to your costs. Your 2026 IRMAA determination is based on your 2024 tax return, filed in early 2025. This is the two-year lookback rule, and it means your pre-retirement income from 2024 is what SSA uses to set your premiums now.

Shortly before or after your Medicare coverage begins, you may receive an Initial IRMAA Determination Notice (sometimes called the IRMAA-D) from the Social Security Administration. This letter states your income-adjusted premium amounts for both Part B and Part D.

If you receive this notice, review the MAGI figure carefully. SSA pulls this number directly from IRS records for tax year 2024. If the figure is correct and your income has since changed due to retirement or another qualifying event, you may be eligible to appeal using Form SSA-44. The appeal window is 60 days from the date on the notice.

If the MAGI figure is incorrect, contact SSA immediately. Errors in IRS data transmission, while uncommon, do occur and can be corrected.

Switching Plans Does Not Reset Your Surcharge

This is worth repeating clearly: IRMAA follows you. It is not tied to a specific plan, insurer, or coverage type. Whether you are on Original Medicare with a standalone Part D plan, a Medicare Advantage plan with built-in drug coverage, or any other combination, the surcharge applies.

Moving from one Medicare Advantage plan to another does not change your IRMAA tier. Dropping a Part D plan and picking up a new one does not reset the surcharge. The only ways to reduce your IRMAA are to lower your MAGI in the lookback year or to appeal through SSA with a qualifying life-changing event.

For a full list of qualifying events and the appeal process, see How to Appeal IRMAA. For strategies that may help reduce future exposure, see IRMAA Avoidance Strategies.

What You Can Control Before Next Enrollment

If open enrollment season is making you aware of IRMAA for the first time, the most important thing to understand is the timeline. Your 2026 IRMAA is already locked, based on your 2024 income. But your 2027 IRMAA will be determined by your 2025 income, and your 2028 IRMAA by your 2026 income.

That means every income decision made this year, from distributions and Roth conversions to asset sales and capital gain harvesting, directly affects what you will pay for Medicare in 2028. The two-year lookback creates a window where proactive planning can make a meaningful difference.

Strategies that are often considered effective include timing Roth conversions to stay below bracket thresholds, using Qualified Charitable Distributions (up to $108,000 per year for those 70.5 and older), tax-loss harvesting to offset gains, and careful sequencing of retirement account withdrawals.

For the complete 2026 bracket thresholds and the exact income lines where each tier begins, see the 2026 IRMAA Brackets page.

It is also worth noting that IRMAA surcharges may qualify as deductible medical expenses on Schedule A if your total medical costs exceed 7.5% of your adjusted gross income. This does not eliminate the surcharge, but it may soften the impact at tax time. Consult a tax professional to determine if this applies to your situation.

Working with an advisor who understands the interaction between income planning and Medicare costs is often the most effective way to manage this exposure over multiple years.

Sources

• Centers for Medicare & Medicaid Services, "2026 Medicare Parts A & B Premiums and Deductibles," cms.gov
• Centers for Medicare & Medicaid Services, "Medicare Open Enrollment Period," medicare.gov
• Social Security Administration, "Medicare Premiums: Rules for Higher-Income Beneficiaries," ssa.gov
• Social Security Administration, "Form SSA-44: Medicare Income-Related Monthly Adjustment Amount, Life-Changing Event," ssa.gov