IRMAA Roth Conversion Sizer
The short answer
A Roth conversion can push your Medicare premiums up for a whole year. For 2026 premiums, based on 2024 MAGI, the first IRMAA cliff starts above $109,000 for a single filer and above $218,000 for a couple filing jointly. One dollar over that line adds $1,148.40 a year for one person with Part B and Part D, or $2,296.80 a year if both spouses are enrolled, according to the CMS 2026 fact sheet. This sizer shows how much headroom you have before the next cliff and the largest taxable conversion that stays in your current tier.
This tool is for information only. It is not legal, tax, or financial advice. Verify current law with the official sources cited before acting.
Size your conversion
Enter your figures before the conversion. All amounts are in US dollars. The calculator sizes against the published 2026 premium-year table, based on 2024 MAGI.
Your IRMAA result
This tool is for information only. It is not legal, tax, or financial advice. Verify current law with the official sources cited before acting.
Enter your figures above and select Calculate to see your tier, headroom, and the largest conversion that stays in your current tier.
How IRMAA and MAGI work
IRMAA stands for the income-related monthly adjustment amount: an extra charge added to Medicare Part B and Part D premiums when income is above set thresholds. CMS states that IRMAA affects roughly 8% of people with Medicare Part B and approximately 8% of people with Medicare Part D.
What counts in MAGI
Your MAGI for IRMAA is your adjusted gross income (Form 1040, line 11) plus your tax-exempt interest income (Form 1040, line 2a). Tax-exempt interest includes municipal bond interest. It counts toward IRMAA even though it is not taxed, which is why this calculator asks for AGI and tax-exempt interest as two separate figures instead of one unexplained income box.
The $1 cliff
IRMAA tiers are cliffs, not gradual steps. MAGI exactly at a threshold stays in the lower tier. One dollar over moves you to the next tier, and you pay that tier's full surcharge for the whole premium year. Part B and Part D each have their own surcharge. If you have both, you pay both. If you have only one benefit, you pay a surcharge only on the benefit you have. Surcharges are charged per person, per month.
The 2-year lookback
Medicare premiums look back 2 years. Premiums for 2026 are based on MAGI from your 2024 tax return, or from 2023 if the 2024 return was not available when the premium was set. A conversion counts toward MAGI in the year you make it, but the surcharge it causes shows up 2 years later. A conversion made in 2026 affects 2028 premiums. In general, the premium year affected is always the conversion year plus 2.
Timing warning: this sizer uses the latest published table, the 2026 premium-year table based on 2024 MAGI. 2027 IRMAA figures had not been published by CMS as of November 12, 2026. The premium year your conversion affects will use different thresholds, which is why the safety buffer matters.
2026 IRMAA table: premiums based on 2024 MAGI
All surcharges below are per person, per month. The standard Part B premium for 2026 is $202.90 a month. The Part D surcharge is added on top of your own plan premium, which varies by plan, so this page never shows a total Part D premium.
| Tier | MAGI, single return | MAGI, joint return | Part B surcharge per month | Total Part B per month | Part D surcharge per month | Combined surcharge per month | Combined surcharge per year |
|---|---|---|---|---|---|---|---|
| Tier 0 (standard) | Up to $109,000 | Up to $218,000 | $0.00 | $202.90 | $0.00 | $0.00 | $0.00 |
| Tier 1 | Over $109,000 to $137,000 | Over $218,000 to $274,000 | $81.20 | $284.10 | $14.50 | $95.70 | $1,148.40 |
| Tier 2 | Over $137,000 to $171,000 | Over $274,000 to $342,000 | $202.90 | $405.80 | $37.50 | $240.40 | $2,884.80 |
| Tier 3 | Over $171,000 to $205,000 | Over $342,000 to $410,000 | $324.60 | $527.50 | $60.40 | $385.00 | $4,620.00 |
| Tier 4 | Over $205,000 and under $500,000 | Over $410,000 and under $750,000 | $446.30 | $649.20 | $83.30 | $529.60 | $6,355.20 |
| Tier 5 (top) | $500,000 or more | $750,000 or more | $487.00 | $689.90 | $91.00 | $578.00 | $6,936.00 |
Yearly figures are the monthly surcharge multiplied by 12. MAGI exactly at a threshold stays in the lower tier.
Married filing separately and lived with your spouse
If you file separately and lived with your spouse at any time during the tax year, use this compressed table. If you lived apart from your spouse all year, use the single-return column in the table above.
| MAGI | Part B surcharge per month | Total Part B per month | Part D surcharge per month |
|---|---|---|---|
| Up to $109,000 | $0.00 | $202.90 | $0.00 |
| Over $109,000 and under $391,000 | $446.30 | $649.20 | $83.30 |
| $391,000 or more | $487.00 | $689.90 | $91.00 |
The middle level combines to $529.60 a month, or $6,355.20 a year, for one person with Part B and Part D.
Extra cost of crossing each cliff
Each step up adds the full difference for the whole premium year. Figures are per person, with Part B and Part D.
| Crossing | Extra per month | Extra per year |
|---|---|---|
| Tier 0 to Tier 1 | $95.70 | $1,148.40 |
| Tier 1 to Tier 2 | $144.70 | $1,736.40 |
| Tier 2 to Tier 3 | $144.60 | $1,735.20 |
| Tier 3 to Tier 4 | $144.60 | $1,735.20 |
| Tier 4 to Tier 5 | $48.40 | $580.80 |
What $1 over the line costs
$1,148.40 per year
For one person crossing the first cliff, with Part B and Part D. Part B only: $974.40 a year.
$2,296.80 per year
For a couple filing jointly crossing the first cliff, when both spouses are enrolled in Part B and Part D. That is Part B $1,948.80 plus Part D $348.00. If only one spouse is enrolled, the cost is $1,148.40 a year.
$6,355.20 per year
For a married-filing-separately filer who lived with a spouse and crosses $109,000 by $1. The compressed table skips the middle tiers, so the jump is more than 5 times the single-filer first-cliff cost.
Worked examples
These examples use the published 2026 premium-year table (2024 MAGI) as illustrations. They are not a promise about any future premium year. Each example assumes the conversion amount shown is the taxable portion, with Part B and Part D enrollment unless stated otherwise.
Example 1: single filer with headroom to the first cliff
MAGI before conversion: $100,000. Headroom to the first cliff: $109,000 minus $100,000 = $9,000. The maximum conversion staying at the standard premium is $9,000, giving MAGI of exactly $109,000. With a $1,000 safety buffer, the maximum is $8,000. Converting $9,001 gives MAGI of $109,001, which is Tier 1, with a surcharge of $1,148.40 for the premium year.
Example 2: couple filing jointly, both spouses enrolled
MAGI before conversion: $200,000. Headroom: $218,000 minus $200,000 = $18,000. The maximum conversion at the standard premium is $18,000, giving MAGI of exactly $218,000. With a $2,000 buffer, the maximum is $16,000. Converting $18,001 gives MAGI of $218,001, which is Tier 1 for each spouse, costing $2,296.80 a year for the household. If only one spouse is on Medicare, the cost is $1,148.40 a year.
Example 3: already in Tier 1, sizing to the second cliff
Single filer with MAGI before conversion of $130,000, already in Tier 1, already owing $1,148.40 a year. Headroom to Tier 2: $137,000 minus $130,000 = $7,000. The maximum added conversion staying in Tier 1 is $7,000. Converting $7,001 more gives MAGI of $137,001, which is Tier 2, with a total surcharge of $2,884.80 a year, an added $1,736.40 a year over Tier 1. As a cross-check, MAGI of $80,000 plus a $40,000 conversion is $120,000, which is Tier 1 at $1,148.40 a year.
Example 4: married filing separately trap
Married filing separately, lived with spouse during the tax year, MAGI before conversion $100,000. Headroom: $109,000 minus $100,000 = $9,000. Converting $9,001 gives MAGI of $109,001, which lands on the compressed table at Tier 4-level surcharges of $529.60 a month, or $6,355.20 a year. If the filer had lived apart all year, the single table would apply instead and the crossing cost would be $1,148.40 a year.
What this sizer does not do
This sizer estimates IRMAA only. It does not estimate:
- Federal or state income tax on the conversion
- Social Security benefit taxability
- The net investment income tax (NIIT)
- Affordable Care Act subsidy effects
- Required minimum distribution (RMD) interaction
- The pro-rata taxable portion of a conversion
Only the taxable portion of a conversion is entered here. If your traditional IRA contains after-tax (nondeductible) basis, the taxable portion is pro-rated across all of your Traditional, SEP, and SIMPLE IRAs on Form 8606. You cannot convert only the after-tax dollars. If all of your traditional IRA money is pre-tax, the taxable portion equals the full conversion. If you have after-tax basis, use the taxable portion from Form 8606 or your tax adviser.
The Part D surcharge is added on top of your plan premium. Plan premiums vary, so this sizer shows the surcharge only and never a total Part D premium.
People with immunosuppressive-drug-only Part B coverage use a separate IRMAA table that is not included here. If that coverage applies to you, check the CMS fact sheet or SSA for the table that applies to you.
Income dropped? Form SSA-44 and life-changing events
Form SSA-44, Medicare Income-Related Monthly Adjustment Amount, Life-Changing Event (current edition December 2025), lets you request a reduction in your IRMAA if you had a major life-changing event and your income has gone down. The eight qualifying events are:
- Marriage
- Divorce or annulment
- Death of your spouse
- Work stoppage
- Work reduction
- Loss of income-producing property, not at your direction, for example a declared-disaster loss, destruction of livestock or crops, arson, or fraud or theft of investment property
- Loss of pension income, through scheduled cessation, termination, or reorganization of an employer's pension plan
- Employer settlement payment, a settlement from an employer or former employer because of bankruptcy or reorganization
The event must fall in the same year or earlier than the more-recent tax year you ask SSA to use. You supply the more-recent year's AGI and tax-exempt interest plus evidence of the event and the income, and SSA checks your statements against IRS records.
A Roth conversion is not a life-changing event. A Roth conversion, capital gain, or other one-time income spike is not one of the eight listed events, so a conversion-caused surcharge generally stands for that premium year and cannot be removed through Form SSA-44. SSA-44 is not part of this calculator's computation.
If you disagree with SSA's determination itself, a separate reconsideration and appeal route exists (Form SSA-561-U2 or an online appeal). That route is different from a life-changing-event request. See Form SSA-44 (PDF) on ssa.gov.
Planning note: the age-63 year
This note follows from simple arithmetic. Part B coverage usually starts at 65, and premiums look back 2 years. That makes the tax year you turn 63 the first income year that can set an IRMAA surcharge when you turn 65.
A conversion made at 63 or 64 can therefore affect your first IRMAA premium. A claim that conversions at 63 or 64 do not trigger any IRMAA because Medicare has not started yet is wrong under the 2-year lookback.
Caveat: if you delay Part B, for example because you have creditable employer coverage past 65, the window slides with your actual Part B start date. Plan from your real start date, not from age 65 alone.
Frequently asked questions
How much can I convert without hitting IRMAA?
It depends on your MAGI before the conversion and your filing status. Find the top of your current tier in the 2026 table, subtract your MAGI before the conversion, and the result is your headroom. This calculator does that subtraction for you, applies your safety buffer, and shows the largest taxable conversion that stays in your current tier. Because $1 over a threshold moves you to the next tier for the whole premium year, most planners leave a buffer for late income surprises.
Does a Roth conversion raise my MAGI for IRMAA?
Enter the taxable portion of your conversion in this calculator, and the calculator adds it to your MAGI to find your tier after the conversion. If all of your traditional IRA money is pre-tax, the taxable portion equals the full conversion. If you have after-tax basis, the taxable portion is figured on Form 8606, so use that figure or one from your tax adviser. A conversion counts in the year you make it, and Medicare premiums look back 2 years, so a 2026 conversion affects 2028 premiums.
What counts toward MAGI for IRMAA?
Your MAGI for IRMAA is your adjusted gross income from Form 1040, line 11, plus your tax-exempt interest income from line 2a. That means municipal bond interest counts toward IRMAA even though it is not taxed. Enter both figures separately in the calculator so nothing is missed.
What happens if I go $1 over an IRMAA threshold?
You move to the next tier for the whole premium year and pay that tier's full monthly surcharge. On the 2026 table, crossing the first cliff costs $1,148.40 a year for one person with Part B and Part D, or $2,296.80 a year for a couple filing jointly when both spouses are enrolled. MAGI exactly at a threshold stays in the lower tier.
Can I appeal an IRMAA surcharge caused by a Roth conversion?
Not through Form SSA-44. That form covers eight listed life-changing events, such as marriage, divorce, death of a spouse, work stoppage, and loss of pension income, and a Roth conversion is not one of them. A conversion-caused surcharge generally stands for that premium year. A separate reconsideration route exists if you disagree with SSA's determination itself, which is different from a life-changing-event request.
Does IRMAA apply to each spouse separately?
Yes. IRMAA is charged per person and per benefit. If you have both Part B and prescription drug coverage, you pay a surcharge on each. If you have only one, you pay a surcharge only on the benefit you have. For a couple filing jointly, the household cost doubles only when both spouses are enrolled, so the calculator asks how many spouses are on Medicare.
What is different if I file separately and lived with my spouse?
You use a compressed table with only three levels instead of six. Above $109,000, you jump straight to Tier 4-level surcharges of $446.30 a month for Part B plus $83.30 a month for Part D, or $6,355.20 a year for one person with both. If you lived apart from your spouse all year, you use the single-return table instead, so the calculator asks which situation applies.
Can I undo a Roth conversion if it pushes me over a cliff?
No. Conversions from a traditional IRA to a Roth IRA made after 2017 cannot be recharacterized, according to IRS Topic No. 309. Size the conversion before you make it, because you cannot take it back to fix an IRMAA tier.
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Sources
- CMS, 2026 Medicare Parts A & B Premiums and Deductibles (fact sheet, released November 14, 2025): full Part B and Part D tables, standard premium, and the roughly 8% figure. cms.gov/newsroom/fact-sheets/2026-medicare-parts-b-premiums-deductibles — accessed November 12, 2026.
- Social Security Administration, Benefits Planner: Retirement, Medicare Premiums (rules for higher-income beneficiaries): 2026 chart, MAGI definition, 2-year lookback, and life-changing events. ssa.gov/benefits/medicare/medicare-premiums.html — accessed November 12, 2026.
- Medicare.gov, 2026 Medicare Costs (CMS Product No. 11579, December 2025): Part B totals and Part D add-ons by 2024 income, all filing statuses. medicare.gov/publications/11579-medicare-costs.pdf — accessed November 12, 2026.
- Social Security Administration, Form SSA-44 (12-2025), Medicare Income-Related Monthly Adjustment Amount, Life-Changing Event: corroborating IRMAA table, MAGI definition, and life-changing events. ssa.gov/forms/ssa-44.pdf — accessed November 12, 2026.
- Internal Revenue Service, Topic No. 309, Roth IRA contributions: conversions may not be recharacterized after 2017. irs.gov/taxtopics/tc309 — accessed November 12, 2026.
Rates and rules verified November 12, 2026 from official sources.