Tax on a $100,000 Roth conversion (2026)
By Mario Bailey · Published · Last reviewed
The federal tax on a Roth conversion depends on what the converted amount stacks on top of. The table below shows the engine's computed incremental federal tax for each combination of filing status and baseline taxable income, not a flat-rate estimate. Each row answers: if your taxable income before the conversion is X, how much additional federal tax does a $100,000 conversion add, and what effective rate does that represent on the conversion?
Federal incremental tax on a $100,000 conversion (2026)
| Filing status | Baseline taxable income | Tax without conversion | Tax with $100,000 conversion | Tax on the conversion | Effective rate on conversion |
|---|---|---|---|---|---|
| Single | $40,000 | $4,552 | $26,198 | $21,646 | 21.65% |
| Single | $80,000 | $12,312 | $35,798 | $23,486 | 23.49% |
| Single | $150,000 | $28,598 | $56,456 | $27,858 | 27.86% |
| Single | $250,000 | $56,456 | $91,269 | $34,813 | 34.81% |
| Married filing jointly | $40,000 | $4,304 | $20,224 | $15,920 | 15.92% |
| Married filing jointly | $80,000 | $9,104 | $29,024 | $19,920 | 19.92% |
| Married filing jointly | $150,000 | $22,424 | $45,196 | $22,772 | 22.77% |
| Married filing jointly | $250,000 | $45,196 | $69,196 | $24,000 | 24.00% |
| Married filing separately | $40,000 | $4,552 | $26,198 | $21,646 | 21.65% |
| Married filing separately | $80,000 | $12,312 | $35,798 | $23,486 | 23.49% |
| Married filing separately | $150,000 | $28,598 | $56,456 | $27,858 | 27.86% |
| Married filing separately | $250,000 | $56,456 | $91,269 | $34,813 | 34.81% |
| Head of household | $40,000 | $4,446 | $24,387 | $19,941 | 19.94% |
| Head of household | $80,000 | $10,501 | $33,987 | $23,486 | 23.49% |
| Head of household | $150,000 | $26,787 | $54,647 | $27,860 | 27.86% |
| Head of household | $250,000 | $54,647 | $89,461 | $34,814 | 34.81% |
A $100,000 conversion and Medicare premiums (IRMAA)
A Roth conversion adds to MAGI dollar for dollar. If the conversion pushes your MAGI above an IRMAA threshold, Medicare Part B and Part D surcharges apply two years later. The table shows the threshold for each filing class and tier, the highest pre-conversion MAGI that avoids crossing it, and the annual surcharge cost per person if you do cross. See full IRMAA brackets for all 2026 thresholds.
| Filing | IRMAA tier | Threshold | Stay under if MAGI below | Cost if crossed (per person / yr) |
|---|---|---|---|---|
| Single / HoH | Tier 1 | $109,000 | $9,000 | $1,148.40 |
| Single / HoH | Tier 2 | $137,000 | $37,000 | $2,884.80 |
| Single / HoH | Tier 3 | $171,000 | $71,000 | $4,620.00 |
| Single / HoH | Tier 4 | $205,000 | $105,000 | $6,355.20 |
| Single / HoH | Tier 5 | $500,000 | $400,000 | $6,936.00 |
| MFJ | Tier 1 | $218,000 | $118,000 | $1,148.40 |
| MFJ | Tier 2 | $274,000 | $174,000 | $2,884.80 |
| MFJ | Tier 3 | $342,000 | $242,000 | $4,620.00 |
| MFJ | Tier 4 | $410,000 | $310,000 | $6,355.20 |
| MFJ | Tier 5 | $750,000 | $650,000 | $6,936.00 |
Does a $100,000 conversion fit in the 22% bracket?
A $100,000 conversion fits within the MFJ 22% bracket width of $110,600 in 2026. A married filer with taxable income between the 22% floor ($100,800) and $111,400 can convert the full $100,000 without leaving the 22% rate.
Two more MAGI lines a $100,000 conversion can cross
Beyond the brackets and IRMAA, a conversion raises MAGI against two other thresholds. Before 65, marketplace premium credits end above 400% of the federal poverty level, a cliff rather than a phase-out; at any age, the 3.8% net investment income tax applies to investment income above a MAGI threshold that never inflation-adjusts. The same stay-under arithmetic applies:
| Threshold | Line | Stay under if other MAGI below | What crossing costs |
|---|---|---|---|
| ACA 400% FPL cliff (single, pre-65) | $62,600 | any MAGI crosses | Entire ACA premium tax credit for the year (pre-65, marketplace coverage) |
| ACA 400% FPL cliff (two-person household, pre-65) | $84,600 | any MAGI crosses | Entire ACA premium tax credit for the year (pre-65, marketplace coverage) |
| NIIT threshold (single) | $200,000 | $100,000 | 3.8% NIIT on investment income up to the overage |
| NIIT threshold (MFJ) | $250,000 | $150,000 | 3.8% NIIT on investment income up to the overage |
The ACA line uses the 2025-vintage poverty guidelines that govern 2026 coverage under IRC §36B(d)(3)(B); the cliff guide works a full example, including the case where one dollar past the line forfeits a four-figure credit.
When to convert the $100,000
A conversion counts for the tax year the money leaves the traditional IRA; December 31 is the deadline and there is no undo. Executing in December sizes the conversion against measured income rather than a forecast, and starts the five-year clock eleven months earlier than a January conversion of the same dollars; the tradeoffs run through the December-versus-January guide. Converting before 59.5 adds the five-year recapture lock on this amount; from 59.5 on, the lock is moot.
State tax on the conversion
State income tax on a Roth conversion ranges from $0 in the nine no-income-tax states to 13.3% in California. Some states with flat income taxes exempt IRA distributions entirely (Illinois at any age, Pennsylvania from age 60), making the state cost zero despite the headline rate. See state taxes on Roth conversions for the breakdown by state, check your specific state page for the computed tax at your income level, or view the full ranked study of all 51 jurisdictions.
FAQ
How much federal tax on a $100,000 conversion?
It depends on what income the conversion stacks on top of. For a married filing jointly filer with $80,000 of existing taxable income, the incremental federal tax on a $100,000 conversion is $19,920, a 19.9% effective rate on the converted amount. For other filing statuses and income levels, see the table above.
Does a $100,000 conversion trigger IRMAA?
For single filers it crosses tier 1 once pre-conversion MAGI exceeds $9,000. For MFJ filers it crosses tier 1 once pre-conversion MAGI exceeds $118,000. Crossing tier 1 adds $1,148.40 per person per year in Medicare surcharges two years later. See the IRMAA table above and /irmaa-brackets/ for full details.