Medicare IRMAA Explained: The Income Surcharge That Can Cost Retirees Thousands

You and your neighbor both have Medicare Part B. You pay $185.00 per month. They pay $628.90 per month. Same coverage, same benefits, same insurance card. The difference? Their income from two years ago was $1 over an IRMAA threshold.

IRMAA — the Income-Related Monthly Adjustment Amount — is Medicare's income-based surcharge system. It's one of the most financially significant details in retirement planning and one of the least understood. Retirees who don't know it exists can receive a surprise bill for thousands of dollars in Medicare premiums that they never planned for. Those who understand it can often avoid it entirely, or at least manage it intelligently.

What Is IRMAA and How Does It Work?

IRMAA is a surcharge applied to both Medicare Part B (medical coverage) and Medicare Part D (prescription drug coverage) premiums for beneficiaries whose income exceeds certain thresholds. The standard Part B premium in 2026 is $185.00/month. IRMAA can more than triple that for high earners.

The surcharge is based on your Modified Adjusted Gross Income (MAGI) — which is your adjusted gross income plus tax-exempt interest, such as income from municipal bonds. Note that tax-exempt interest counts even though it isn't subject to income tax.

The 2-year lookback is what makes IRMAA particularly tricky. Your 2026 Medicare premiums are determined by your 2024 income. You won't find out your 2026 IRMAA determination until late 2025 — based on a year that may already be locked in. By the time you receive the letter, there's nothing you can do about that year's income. The window to plan is always two years before the premiums hit.

IRMAA operates as a cliff structure, not a gradual bracket. Cross a threshold by $1 and you owe the full surcharge for that tier — for the entire year. This is categorically different from income tax brackets, where only the income above the threshold faces the higher rate. With IRMAA, every dollar of income matters, and a small, unexpected income event can cost thousands.

2026 IRMAA Brackets

The thresholds below determine your Part B and Part D surcharges for 2026, based on 2024 MAGI:

Single Filers:

| 2024 MAGI | Monthly Part B Premium | Annual Household Cost | |---|---|---| | ≤ $106,000 | $185.00 | $2,220 | | $106,001–$133,000 | $259.00 | $3,108 | | $133,001–$167,000 | $370.00 | $4,440 | | $167,001–$200,000 | $481.00 | $5,772 | | $200,001–$499,999 | $553.50 | $6,642 | | $500,000+ | $628.90 | $7,547 |

Married Filing Jointly:

| 2024 MAGI | Monthly Part B Premium (per person) | Annual Household Cost (2 people) | |---|---|---| | ≤ $212,000 | $185.00 | $4,440 | | $212,001–$266,000 | $259.00 | $6,216 | | $266,001–$334,000 | $370.00 | $8,880 | | $334,001–$400,000 | $481.00 | $11,544 | | $400,001–$749,999 | $553.50 | $13,284 | | $750,000+ | $628.90 | $15,094 |

Part D surcharges add further costs at each tier. And Married Filing Separately faces a uniquely punitive structure — the single thresholds apply but with only two tiers, meaning income over $106,000 lands you immediately at Tier 4.

The IRMAA Cliff Problem

The cliff structure creates a harsh planning reality. Consider a married couple with 2024 MAGI of $211,999. They pay the standard $185.00/month per person — $4,440/year for both. Now suppose they have one additional dollar of income — a slightly larger required minimum distribution, a small capital gain, or even just interest income they forgot to account for. Their MAGI becomes $212,001.

That one dollar triggered the first IRMAA tier. Their Part B premium jumps to $259.00/month per person, plus Part D surcharges. The total annual impact for a couple: roughly $1,776 more per year in Part B alone, plus Part D. A single dollar cost them nearly $2,000.

The problem is that the income events that commonly push people over IRMAA thresholds are exactly the ones that seem financially harmless:

• A Roth conversion (increases MAGI directly)
• Selling appreciated stock or real estate (capital gains count)
• Municipal bond interest (tax-exempt but counted in MAGI)
• A larger-than-expected RMD due to good market returns
• An inheritance or settlement payment received in an earlier year

And because of the two-year lookback, by the time you find out you crossed a threshold, the income decision that caused it is two years in the past.

What Counts Toward IRMAA — and What Doesn't

Counts toward MAGI (and therefore IRMAA):

• Wages and self-employment income
• Traditional IRA and 401(k) withdrawals
• Pension and annuity income
• Social Security benefits (the taxable portion)
• Capital gains from stocks, real estate, and other assets
• Rental income
• Tax-exempt interest (municipal bonds)
• RMDs from inherited IRAs

Does NOT count toward MAGI:

• Qualified Roth IRA and Roth 401(k) withdrawals
• HSA distributions used for qualified medical expenses
• Return of basis from non-qualified annuities
• Life insurance death benefits
• Loan proceeds (including reverse mortgage draws)
• Veterans' benefits

The most important item on the second list is Roth withdrawals. Money you've already paid tax on and moved to a Roth account is invisible to IRMAA. This is one of the most significant planning advantages of Roth accounts in retirement — and one of the core reasons that building Roth balances during working years, or during the Roth conversion window, can pay outsized dividends decades later.

6 Strategies to Avoid or Reduce IRMAA

1. Know Exactly Where You Stand

The first step is knowing your current MAGI, your proximity to the next IRMAA threshold, and what income events are coming. Guessing doesn't cut it here — the cliff structure makes precision important. The Medicare IRMAA Calculator shows your current tier, your headroom before the next cliff, and lets you model the impact of any planned income event before you take it.

2. Time Roth Conversions Before Age 63

Roth conversions increase your MAGI in the year of conversion and will affect your IRMAA two years later. If you enroll in Medicare at 65, conversions done at age 63 or later will show up in your Medicare premiums. Conversions done before age 63 clear the two-year lookback window and don't affect your Part B premiums at all. The earlier you start converting — during the low-income window between retirement and RMDs — the more you can convert before the IRMAA clock becomes relevant.

3. Use QCDs to Reduce MAGI After 70½

If you're 70½ or older, Qualified Charitable Distributions let you send money directly from your IRA to a qualifying charity. The distribution counts toward your RMD but never enters your AGI, which means it doesn't affect MAGI or IRMAA. For retirees who are charitably inclined anyway, this can materially reduce MAGI in high-income years.

4. Harvest Capital Gains Strategically

Capital gains from selling appreciated assets add directly to MAGI. If you're near an IRMAA threshold, consider spreading large sales across multiple tax years rather than realizing them all in one year. Selling in a year when your other income is low can minimize or eliminate the IRMAA impact.

5. Use Roth Funds and HSAs in High-Income Years

In years when you have unavoidable income spikes — a large RMD, a business sale, an inheritance — lean on Roth withdrawals and HSA distributions for discretionary spending. Since neither counts toward MAGI, using them strategically keeps MAGI lower during the years that will determine your IRMAA two years out.

6. Appeal with Form SSA-44 After a Life-Changing Event

If your income dropped significantly because of a qualifying life event — retirement, divorce, death of a spouse, or loss of income-producing property — you can request that the Social Security Administration use a more recent year's income instead of the two-year lookback. File Form SSA-44 with documentation of the event. This is especially valuable for newly retired people who earned a high salary in their final working year but have substantially lower income now.

IRMAA and Roth Conversions — The Planning Paradox

Here's the tension: Roth conversions are one of the best strategies to reduce long-term IRMAA exposure. But done in the wrong year, they can trigger it.

Converting $50,000 from a traditional IRA to a Roth IRA this year increases your MAGI by $50,000. If that pushes you over an IRMAA threshold, you'll pay surcharges for the following two years. The conversion might still make financial sense — if the long-term tax savings exceed the IRMAA cost — but you need to model both sides of the equation.

The timing key: convert before Medicare enrollment. Specifically, before age 63 if you plan to enroll in Medicare at 65. That gives the two-year lookback time to clear. If you're already on Medicare, conversions can still be rational — but you need to weigh the IRMAA surcharge cost against the tax savings from converting at today's rates rather than future rates when RMDs force withdrawals.

The Roth Conversion Ladder Planner can help you model this tradeoff: it factors in IRMAA thresholds, Social Security taxation, and bracket ceilings to find the annual conversion amount that optimizes your lifetime tax bill.

The Bottom Line

IRMAA is one of the most overlooked costs in retirement planning, largely because it's invisible until it hits. The two-year lookback means that by the time you see the surcharge, the income decision that caused it is already history.

The good news is that IRMAA is entirely manageable with proactive planning. The key elements are: knowing your thresholds, timing income events around them, building Roth balances that won't count against you, and having a plan for what to do when large income events are unavoidable.

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This article is for educational purposes only and does not constitute tax, financial, or legal advice. Medicare rules and premiums change annually — verify all figures with a qualified professional before making financial decisions.