The roth conversion impact on medicare premiums works through one mechanism: a conversion is taxable ordinary income, that income raises your modified adjusted gross income (MAGI), and MAGI is exactly what Medicare uses to decide whether you pay an income surcharge on Part B and Part D two years later. If your conversion pushes your MAGI across an income threshold, your premiums rise for a single year.
A Roth conversion is taxed as ordinary income and adds to your MAGI, which can trigger the Income-Related Monthly Adjustment Amount (IRMAA), a surcharge on Medicare Part B and Part D. Because IRMAA uses a two-year lookback, a 2026 conversion affects 2028 premiums. The 2026 standard Part B premium is $202.90 per month, with the first IRMAA tier starting above $109,000 (single) or $218,000 (joint) MAGI. (Source: CMS 2026 Fact Sheet; SSA POMS HI 01101.020)
What IRMAA is, in plain English
IRMAA stands for the Income-Related Monthly Adjustment Amount. It is a surcharge added on top of the standard Medicare Part B premium and, separately, on top of your Medicare Part D drug plan premium, for beneficiaries whose income sits above set thresholds. It has adjusted Part B premiums by income since 2007 and reaches roughly 8% of Part B beneficiaries (Source: SSA Benefits Planner; CMS 2026 Fact Sheet, treated as approximate).
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For 2026, the standard Part B premium is $202.90 per month, up from $185.00 in 2025, and the annual Part B deductible is $283 (Source: CMS “2026 Medicare Parts A & B Premiums and Deductibles,” Nov 14, 2025). Anyone whose MAGI stays below the first threshold pays that standard $202.90 with no Part B surcharge and no Part D surcharge. Cross the threshold, and IRMAA is added on both parts.
One detail that surprises couples: IRMAA is assessed per beneficiary. If both spouses are enrolled in Medicare and the household MAGI lands in a surcharge tier, each spouse pays the surcharge separately (Source: SSA POMS HI 01101.020). A single high-income year can therefore mean two surcharges in one household.
How a Roth conversion raises your MAGI
When you convert traditional IRA or 401(k) dollars to a Roth, the converted amount is taxed as ordinary income in the conversion year and flows into your adjusted gross income. For IRMAA, MAGI equals AGI (Form 1040, line 11) plus tax-exempt interest (line 2a), so a conversion adds dollar-for-dollar to the figure Medicare measures (Source: SSA POMS HI 01101.010). There is no income cap and no dollar limit on how much you can convert.
A Roth conversion moves money from a tax-deferred account into a Roth IRA, where future growth and qualifying withdrawals are tax-free. The trade is that you pay ordinary income tax now on the amount converted. Because that income is fully reportable, it raises your AGI, and IRMAA MAGI is built directly from AGI. Tax-exempt municipal bond interest, which some retirees hold to keep taxable income down, is added back for the IRMAA calculation, so it does not shelter you from the threshold math.
This is why the roth conversion impact on medicare premiums is so direct. Unlike a qualified Roth withdrawal, which never counts as income, the conversion event itself is the taxable moment. A large conversion in a single year can move a retiree from paying no IRMAA to paying the highest tier.
The two-year lookback: a 2026 conversion sets 2028 premiums
Medicare does not use current income to set IRMAA. It uses your most recent federal return on file, generally the return from two years prior. So 2026 IRMAA is based on 2024 income, and a conversion you do in 2026 will set your Part B and Part D surcharges for 2028 (Source: SSA POMS HI 01101.030). If two-year-prior data is unavailable, SSA may use three-year-prior data.
The lookback is a commonly misunderstood part of this topic. Retirees often expect a surcharge letter the same year they convert, then feel blindsided two years later. The practical planning point is that a conversion done in 2026 does not touch your 2026 or 2027 premiums at all; it lands in 2028. That two-year gap is also why timing conversions before you enroll in Medicare matters, covered further below.
2026 IRMAA brackets: Part B and Part D by filing status
The 2026 IRMAA tables use MAGI from two years prior. Below is the sliding scale for single and married-filing-jointly filers, showing the total monthly Part B premium (standard $202.90 plus surcharge) and the Part D surcharge added to your drug plan premium (Source: SSA POMS HI 01101.020, updated Dec 2, 2025). Thresholds are indexed to inflation each year, except the top single and joint tiers, which are statutorily fixed.
| Single / HOH MAGI (2024 income) | MFJ MAGI (2024 income) | Total Part B / month | Part D surcharge / month |
|---|---|---|---|
| $109,000 or less | $218,000 or less | $202.90 (no IRMAA) | $0.00 |
| >$109,000 to $137,000 | >$218,000 to $274,000 | $284.10 | +$14.50 |
| >$137,000 to $171,000 | >$274,000 to $342,000 | $405.80 | +$37.50 |
| >$171,000 to $205,000 | >$342,000 to $410,000 | $527.50 | +$60.40 |
| >$205,000 to <$500,000 | >$410,000 to <$750,000 | $649.20 | +$83.30 |
| $500,000 or more | $750,000 or more | $689.90 | +$91.00 |
Married filing separately follows a compressed scale: MAGI above $109,000 to under $391,000 pays $649.20 for Part B plus a $83.30 Part D surcharge, and $391,000 or more pays $689.90 plus $91.00 (Source: SSA POMS HI 01101.020). A separated filer who lived apart from their spouse for the entire year may use the single table instead. For a fuller breakdown, see the 2026 Medicare IRMAA brackets guide.
The cliff effect: one dollar can cost you the whole tier
IRMAA is a cliff, not a gradual phase-in. Crossing a threshold by a single dollar moves you into the next tier’s full surcharge for all 12 months of the year (Source: SSA POMS HI 01101.020, which uses discrete brackets with no interpolation). A conversion that lands your MAGI $1 over a line can cost the same as one that lands you thousands over it, which is why conversion sizing is precise work.
Consider a single retiree with MAGI at $137,000 versus $137,001. The first pays $284.10 per month for Part B; the second pays $405.80, roughly $121.70 more each month, or about $1,460 more over the year, plus a larger Part D surcharge, all triggered by one extra dollar of income. This is the opposite of the marginal tax brackets most people picture, where only the dollars above a line are taxed at the higher rate. With IRMAA, the entire year’s surcharge steps up at once.
Worked examples: what a $100,000 and $200,000 conversion can cost
The following two scenarios are hypothetical illustrations, not real clients or projections. They use 2026 IRMAA figures to show how a conversion moves MAGI across tiers and what the resulting Part B and Part D surcharges would be for the year the conversion sets, two years later.
Hypothetical single filer, $100,000 conversion
Assume a single retiree with a baseline MAGI of $90,000, which is below the $109,000 first threshold, so with no conversion they would pay no IRMAA. They convert $100,000. Their MAGI rises to $190,000, landing in the >$171,000 to $205,000 tier.
- Part B jumps from $202.90 to $527.50 per month, a surcharge of $324.60 per month, about $3,895 for the year.
- Part D adds a $60.40 monthly surcharge, about $725 for the year.
- Combined IRMAA attributable to the conversion: roughly $4,620 for that single year.
Hypothetical married couple, $200,000 conversion
Assume a couple, both enrolled in Medicare, with a baseline joint MAGI of $120,000 and no IRMAA. They convert $200,000, lifting MAGI to $320,000, which lands in the MFJ >$274,000 to $342,000 tier. Because IRMAA is per beneficiary, each spouse pays a surcharge.
- Each spouse’s Part B rises to $405.80 per month, a surcharge of $202.90 each, about $2,435 per person for the year.
- Each spouse’s Part D adds $37.50 per month, about $450 per person.
- Two beneficiaries combined: roughly $5,770 in IRMAA for that single year.
These surcharges apply for one year, then reset once your MAGI returns to its normal level. The IRMAA cost of a conversion is a one-year event, not a permanent increase.
Calculate your own conversion ceiling
Your “conversion ceiling” is the amount you can convert before your MAGI crosses the next IRMAA threshold. The method: project your MAGI for the conversion year without the conversion, then subtract that from the next threshold for your filing status. The difference is your headroom under that cliff. This is a repeatable calculation you can run every tax year with your own numbers.
Here is the process as a worksheet:
- Estimate your MAGI for the year without any conversion: pensions, interest, dividends, Social Security that is taxable, RMDs if applicable, and add back tax-exempt interest.
- Identify the IRMAA threshold you want to stay under for your filing status from the 2026 table above.
- Subtract your projected MAGI from that threshold. The result is your headroom, the largest conversion that keeps you under that cliff.
- Remember the two-year lookback: the ceiling you calculate for a 2026 conversion protects your 2028 premiums.
Single example. Projected MAGI is $95,000. To avoid any IRMAA, the ceiling is the first threshold, $109,000, minus $95,000, which is $14,000. To instead fill the first surcharge tier and stop before the second cliff at $137,000, the ceiling would be $42,000.
Married example. A couple’s projected joint MAGI is $180,000. To avoid any IRMAA, the ceiling is $218,000 minus $180,000, which is $38,000 of conversion room before the first joint cliff.
Filling a tier deliberately, rather than avoiding IRMAA entirely, is a common approach when the goal is to reduce future RMDs. Deciding how much to convert in any year is where the IRMAA ceiling and your marginal tax bracket both matter.
The pre-Medicare window: ages 59 to 63
Conversions completed before you enroll in Medicare have no IRMAA effect on you, because there is no premium to surcharge yet. Given the two-year lookback, income in the year you turn 63 is what first sets IRMAA for the year you turn 65. Many retirees treat the roughly age 59 to 63 window, after early-withdrawal penalties end but before that lookback bites, as the lowest-friction time to convert.
This window is often a clean opportunity in a conversion plan. Between age 59.5, when the 10% early-distribution penalty no longer applies, and the year you turn 63, a conversion adds to your income tax bill but carries no IRMAA consequence, because your first Medicare premium year has not yet entered the lookback. Retirees who have already stopped working but not yet claimed Social Security sometimes find these are their lowest-income years, which can make the tax cost of converting lower as well.
Is one year of IRMAA worth it?
The honest way to weigh it is as a one-time toll against a lifetime cost. IRMAA from a conversion is finite: it applies for the single year your MAGI is raised, then resets. The tax drag from required minimum distributions is not finite; it can recur every year for the rest of your life and your spouse’s. Comparing a one-year surcharge to a multi-decade RMD stream is the core trade-off.
Converting before RMDs begin reduces the traditional IRA balance that will later be forced out as taxable income. Under current law, RMDs begin at age 73 (age 75 for those born in 1960 or later, starting in 2033) (Source: IRS, SECURE 2.0 Act RMD rules). Those distributions raise MAGI every year, which can push IRMAA higher year after year, and they cannot be avoided once they start, aside from qualified charitable distributions.
So the framing is not “does a conversion raise my Medicare premium” in isolation. It is whether accepting a one-year surcharge now is preferable to a potentially larger and repeating IRMAA and income-tax exposure later. The answer depends on your balances, tax bracket, and time horizon, and the math cuts both ways. A Roth conversion break-even analysis and a review of your projected required minimum distributions are the two pieces that make this concrete for a given household. This is educational information, not a recommendation to convert.
The tax torpedo: Social Security interaction
For retirees already claiming Social Security, a conversion can do double damage in the conversion year. The added income can raise the share of Social Security benefits that is taxable (through the provisional-income formula) and can push MAGI into an IRMAA tier at the same time. This combined effect is often called the tax torpedo, and it is a reason some retirees convert before claiming benefits.
Provisional income determines how much of your Social Security is subject to income tax, up to 85%. A conversion inflates that figure, so a dollar converted can increase both your ordinary tax and the tax on benefits you are already receiving, while separately affecting IRMAA. The interaction is why conversion timing relative to your Social Security start date matters. For the mechanics, see how the taxation of Social Security benefits works alongside conversion income.
Can you appeal IRMAA caused by a conversion?
Generally, no. IRMAA can be reduced only for a qualifying “life-changing event” filed on Form SSA-44, and a voluntary Roth conversion is not on that list (Source: SSA POMS HI 01120.005; Form SSA-44, 12-2025). The qualifying events are things outside your control, such as work stoppage or loss of a pension. Because a conversion is a chosen action, the resulting surcharge is not appealable, which makes sizing the conversion correctly the only real control you have.
The eight qualifying life-changing events on Form SSA-44 are: marriage; divorce or annulment; death of a spouse; work stoppage; work reduction; loss of income-producing property beyond your control; loss or reduction of certain pension income; and an employer settlement payment (Source: SSA “Request to lower IRMAA”; SSA POMS HI 01120.005). None of these covers voluntary conversion income. Setting this expectation honestly matters: if you convert and cross a threshold, you cannot later ask Social Security to undo the surcharge on the grounds that it was a one-time event. The planning happens before the conversion, not after the premium letter arrives.
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Q3 Advisors is a registered investment adviser focused on retirement tax planning. This article is educational and is not advice; for guidance on your own circumstances, consult a qualified tax or financial professional.
Frequently asked questions
These answers summarize how a Roth conversion interacts with Medicare IRMAA surcharges, drawn from the SSA and CMS sources cited above. They cover whether a conversion counts as income, how long a surcharge lasts, the two-year lookback timing, how much you can convert under a threshold, and whether the resulting surcharge can be appealed. This is educational information, not personalized advice.
Does a Roth conversion count as income for IRMAA and Medicare?
Yes. A Roth conversion is taxed as ordinary income and adds to your adjusted gross income, and IRMAA MAGI equals AGI plus tax-exempt interest (Source: SSA POMS HI 01101.010). The full converted amount counts, with no dollar or income cap. That is the direct link between a conversion and a possible Medicare Part B and Part D surcharge two years later.
How many years does a Roth conversion affect my Medicare premiums?
One year. IRMAA is assessed on the MAGI from a single tax year, so a one-time conversion raises premiums only for the one year that raised income governs, then resets once your MAGI returns to normal (Source: SSA POMS HI 01101.020). Because of the two-year lookback, that surcharge year falls two years after the conversion year.
At what age do Roth conversions stop affecting IRMAA?
Conversions affect IRMAA only once your income year enters Medicare’s two-year lookback. Income in the year you turn 63 first sets IRMAA for the year you turn 65. Conversions done before then, in the roughly age 59 to 63 window, carry no IRMAA impact because you are not yet paying Medicare premiums (Source: SSA POMS HI 01101.030).
How much can I convert without triggering IRMAA?
Subtract your projected MAGI for the year from the next IRMAA threshold for your filing status; the difference is the largest conversion that stays under that cliff. For 2026 the first thresholds are $109,000 single and $218,000 joint (Source: SSA POMS HI 01101.020). A retiree with $95,000 single MAGI has $14,000 of room before the first surcharge tier.
Does IRMAA apply the year of the conversion or two years later?
Two years later. Medicare sets IRMAA using your most recent return on file, generally the return from two years prior, so a 2026 conversion affects your 2028 Part B and Part D premiums, not your 2026 premiums (Source: SSA POMS HI 01101.030). This gap surprises many retirees, who expect the surcharge in the conversion year itself.
Do Roth conversions raise both Part B and Part D premiums?
Yes. When MAGI crosses an IRMAA threshold, a surcharge is added to Part B and, separately, to your Part D drug plan premium. In the 2026 tables the two surcharges rise together at each tier, for example a $60.40 monthly Part D surcharge accompanies the third single-filer tier (Source: SSA POMS HI 01101.020).
Can I appeal a higher Medicare premium caused by a conversion?
Generally no. IRMAA can be reduced only through Form SSA-44 for a qualifying life-changing event, and a voluntary Roth conversion is not one of them (Source: SSA POMS HI 01120.005; Form SSA-44). Qualifying events include work stoppage, divorce, or loss of a pension, all outside your control. Chosen conversion income does not qualify, so sizing the conversion in advance is the only lever.
Is a Roth conversion still worth it if it raises my Medicare premiums?
It depends on your situation. The IRMAA surcharge is a one-year cost, while the income-tax drag from future required minimum distributions can recur for life. Weighing a finite surcharge against a lifetime RMD stream is the central trade-off (Source: SSA POMS HI 01101.020; 2026 RMD age 73). This is educational information, not a recommendation; a personalized analysis is the right way to decide.
Sources
CMS, “2026 Medicare Parts A & B Premiums and Deductibles” Fact Sheet (Nov 14, 2025). cms.gov/newsroom/fact-sheets
SSA POMS HI 01101.020, “IRMAA Sliding Scale Tables” (updated Dec 2, 2025). secure.ssa.gov/poms
SSA POMS HI 01101.010, “Modified Adjusted Gross Income (MAGI)”
SSA POMS HI 01101.030, “Two-Year Lookback / IRS Data”
SSA POMS HI 01120.005, “Life-Changing Events”
SSA, “Request to lower an Income-Related Monthly Adjustment Amount” and Form SSA-44 (12-2025). ssa.gov/medicare/lower-irmaa
SSA Benefits Planner, “Medicare Premiums”. ssa.gov/benefits/medicare/medicare-premiums.html
IRS, retirement plan contribution and RMD figures for 2026.
