How Medicare IRMAA Surcharges Can Silently Erode Your Retirement

2026 IRMAA Brackets: Part B Monthly Premiums

Based on 2024 MAGI. Standard Part B premium: $202.90/month.

Most Medicare beneficiaries pay a standard premium for Part B and Part D. But Medicare was designed so that higher-income retirees cover a bigger share of the program’s costs. Think of it like a toll road with income-based pricing. Everyone gets the same road, but the toll booth checks your tax return and charges accordingly.

The Two-Year Lookback Rule

IRMAA uses a two-year lag. The Social Security Administration pulls your Modified Adjusted Gross Income from the tax return filed two years before the current premium year. So your 2026 IRMAA is based on your 2024 MAGI, which you reported to the IRS in early 2025. Your 2025 IRMAA was based on 2023 income.

This delay is what catches people off guard. A one-time windfall in 2024 — selling a rental property, a large Roth conversion, exercising stock options — won’t show up as higher Medicare premiums until 2026. By then, most people have forgotten about the income event that triggered it.

What Counts as MAGI for IRMAA?

The MAGI that Medicare uses isn’t exactly the same as the MAGI used for other tax purposes. For IRMAA, it’s your Adjusted Gross Income (line 11 on Form 1040) plus any tax-exempt interest income (line 2a). That second piece is the one people miss. Municipal bond interest, which doesn’t show up in your taxable income, still counts toward IRMAA thresholds.

A few things that flow into IRMAA-relevant MAGI: wages, pension income, IRA and 401(k) distributions (including Roth conversions), capital gains, rental income, Social Security benefits (the taxable portion), and tax-exempt interest. Contributions to an HSA or traditional IRA can reduce your AGI, but only if you’re still eligible to make them.

The Cliff Effect: Why $1 Can Cost $1,000

IRMAA brackets work like cliffs, not slopes. There’s no gradual phase-in. If a single filer’s 2024 MAGI was $109,000, they pay the standard $202.90 in 2026. At $109,001, they jump to $284.10. That single dollar costs an extra $974.40 over the year. For a married couple where both spouses are on Medicare, that same dollar would cost them $1,948.80.

This cliff structure is why IRMAA planning focuses so heavily on staying just below bracket thresholds rather than minimizing income overall.

The raw bracket tables show monthly premiums, but what really matters is the annual cost. And when both Part B and Part D surcharges are combined, the total hit can be substantial. Here’s how the 2026 numbers stack up for a single filer.

Annual Cost by IRMAA Tier (2026, Single Filer)

At Tier 1, the extra cost is manageable: about $81 more per month for Part B. But at Tier 4, a single person is paying an extra $446 per month in Part B alone, plus another $79 for Part D. That’s over $6,300 a year in surcharges on top of the standard premium.

The Married Couple Math

When both spouses have Medicare, IRMAA doubles. A married couple filing jointly with $220,000 in MAGI (just $2,000 over the first threshold) would each pay $284.10 per month for Part B, totaling $6,818 per year. That’s $1,949 more than two standard premiums would cost.

And here’s where it gets especially painful for couples: married-filing-separately filers face a compressed bracket structure. Only two tiers exist for MFS. Between $109,000 and $391,000, the Part B premium jumps straight to $649.20 per month. That’s the equivalent of Tier 4 for joint filers. Filing separately almost never helps with IRMAA.

Two Retirees, Very Different Premiums

Frank’s Roth conversion added $32,000 in MAGI. That pushed him past two bracket thresholds at once, costing an extra $2,435 per year in Part B alone. The conversion might still be worth it in the long run (Roth withdrawals won’t trigger IRMAA in future years), but the two-year premium hit is real and needs to be part of the math.

The cliff structure of IRMAA creates a strange reality: sometimes earning $1 less is worth hundreds or thousands of dollars. That dynamic shapes most of the planning around it. But there are also situations where absorbing the surcharge makes sense, and a formal appeal process for when life events change your income picture.

How Do Roth Conversions Affect IRMAA?

The most common IRMAA trigger for retirees is the Roth conversion. Converting traditional IRA money to a Roth adds the entire converted amount to your AGI in the year of conversion. Two years later, that inflated MAGI hits your Medicare premiums.

The tradeoff is real, though. Roth conversions done strategically before age 65 — or in lower-income years — can permanently reduce future IRMAA exposure because qualified Roth distributions don’t count as income at all. The question is whether the short-term premium hit is worth the long-term savings. For someone planning to do conversions anyway, spreading them across multiple years to stay within a single IRMAA tier (or below the first threshold entirely) can save thousands compared to one large conversion.

The optimal conversion window is typically ages 60–63, after retirement income drops but before Medicare begins. Income decisions in this window affect premiums two years later — so a 63-year-old’s Roth conversion strategy directly shapes what they pay at 65.

What Else Reduces MAGI — and IRMAA?

Capital gains timing is another big lever. Selling appreciated stock or real estate in a single year can spike MAGI well above normal. Harvesting losses in the same year, or spreading sales across tax years, can keep income below a bracket threshold.

Qualified Charitable Distributions (QCDs) let people aged 70½ and older donate up to $105,000 per year directly from an IRA to a qualifying charity. The distribution satisfies RMD requirements but doesn’t count as taxable income. For retirees who donate anyway, QCDs are one of the most effective ways to keep MAGI down — and one of the few tools available after Medicare has already begun.

Municipal bond interest is often a surprise. It’s tax-free for income tax purposes, but it still counts toward IRMAA MAGI. A retiree sitting on a large muni bond portfolio might have lower taxable income than expected but still trip an IRMAA bracket because of Line 2a on their 1040.

How to Appeal IRMAA Using Form SSA-44

Sometimes a two-year-old tax return doesn’t reflect your current reality. If your income dropped significantly because of a qualifying life-changing event, the SSA allows you to request a new IRMAA determination using more recent income. The qualifying events include: marriage, divorce or annulment, death of a spouse, work stoppage or reduction, loss of income-producing property (due to disaster or other event), and loss of pension income.

The form to file is SSA-44. It asks for documentation of the event and an estimate of your current-year MAGI. The SSA reviews the request and can adjust your premiums accordingly. This won’t help with a planned Roth conversion or voluntary capital gain — those aren’t qualifying events — but it’s highly effective for genuinely unexpected income drops.

Should You Try to Avoid IRMAA or Just Pay It?

Not every IRMAA hit is worth avoiding. If a retiree needs to take a large IRA distribution to cover a home purchase, or if selling a business pushes income well above the thresholds for just one year, the cost of IRMAA might be small relative to the benefit of the transaction. The key factor is whether the income event is a one-time spike or an ongoing pattern.

A one-time jump into Tier 2 costs about $2,435 extra for the year (for Part B alone). If that same event generates $100,000 in needed cash, the IRMAA cost is roughly 2.4% of the proceeds. Annoying, but probably not a reason to restructure the transaction.

On the other hand, consistently sitting just above a bracket year after year adds up fast. Ten years of avoidable Tier 1 surcharges is nearly $10,000 in extra premiums that a small income adjustment could have prevented.

Plug in your expected income to see which 2026 IRMAA bracket you’d fall into and what your total Medicare premiums would look like. The calculator uses current-year thresholds, which are a reasonable guide for near-term planning.

Quick Start Calculator

What to Look For in the Results

Your current bracket tells you what you’re paying now and how close you are to the next cliff. If you’re within a few thousand dollars of a threshold, even small income adjustments — a slightly smaller RMD, a QCD, deferring a capital gain — could drop you to a lower tier. The annual premium impact shows the total extra cost of being in your bracket versus the standard premium, which helps frame whether it’s worth restructuring income to avoid. The two-year projection maps your expected income in the current year to the premiums you’ll pay two years from now, so there are no surprises when the SSA letter arrives. And the Roth conversion sweet spot shows how much you can convert while staying within your current IRMAA tier, turning a blunt guessing game into a specific dollar target.

Disclaimer: This calculator provides estimates for educational purposes only. Actual IRMAA determinations are made by the Social Security Administration based on IRS tax data. Bracket thresholds are adjusted annually for inflation, so future-year brackets may differ from current figures. This tool does not account for life-changing event appeals or state-specific Medicare supplement costs. For official determinations, contact the SSA at 1-800-772-1213 or visit ssa.gov.