Free calculator
Roth Conversion Tax Calculator (2026)
See the federal income tax on moving traditional IRA or 401(k) savings to a Roth this year, the bracket it lands in and the room left in it, and what it does to your Social Security taxes and Medicare premiums. No sign-up needed.
Pensions, wages, IRA withdrawals and RMDs, interest and ordinary dividends. Leave out the conversion.
From a traditional IRA or pre-tax workplace plan to a Roth IRA.
Federal tax on this conversion
$4,896
12.2% of the $40,000 you convert.
Top tax bracket
12%
$7,500 more could be converted before income reaches the 22% bracket.
- The conversion makes $800 more of your Social Security taxable.
Medicare premiums
Your 2026 income (MAGI) would be $140,800, $77,200 below the $218,000 threshold where Medicare surcharges for 2028 begin.
Your 2026 return, with and without the conversion
| Line | Without | With conversion |
|---|---|---|
| Taxable Social Security | $40,000 | $40,800 |
| Adjusted gross income | $100,000 | $140,800 |
| Standard deduction | $35,500 | $35,500 |
| Senior deduction | $12,000 | $12,000 |
| Taxable income | $52,500 | $93,300 |
| Federal income tax | $5,804 | $10,700 |
Federal income tax only, with the standard deduction. Medicare figures use 2026 thresholds; the 2028 ones will likely be higher. Counts people who will be 65 by 2028 (age 63 or older now).
The method
How the tax on a conversion is figured
The calculator works out your 2026 federal income tax twice, with and without the conversion, and the difference is what the conversion costs. Each time it adds up your income, works out how much of your Social Security is taxable, subtracts the standard deduction and the senior deduction, and applies the 2026 brackets.
For a married couple, both 67, with $48,000 of Social Security and $60,000 of other income, converting $40,000:
- Tax with the conversion
- $10,700
- Tax without it
- − $5,804
- Tax on the conversion
- $4,896
That is 12.2% of the amount converted, a little over their 12% bracket, because the conversion also makes $800 more of their Social Security taxable. They could convert $7,500 more before reaching the 22% bracket.
2026 brackets
2026 federal tax brackets
Rates apply to taxable income, after deductions. Each rate covers only the income inside its band.
| Rate | Single | Married filing jointly |
|---|---|---|
| 10% | Up to $12,400 | Up to $24,800 |
| 12% | $12,400 to $50,400 | $24,800 to $100,800 |
| 22% | $50,400 to $105,700 | $100,800 to $211,400 |
| 24% | $105,700 to $201,775 | $211,400 to $403,550 |
| 32% | $201,775 to $256,225 | $403,550 to $512,450 |
| 35% | $256,225 to $640,600 | $512,450 to $768,700 |
| 37% | Over $640,600 | Over $768,700 |
The 2026 standard deduction is $16,100 for single filers and $32,200 for joint filers. At 65 or older it rises by $2,050 for a single filer or $1,650 for each spouse, and the $6,000 senior deduction comes on top.
Hidden costs
Why a conversion can cost more than your bracket
More of your Social Security becomes taxable
Benefits start to be taxed when your other income plus half your benefits passes $25,000 ($32,000 joint). Above $34,000 ($44,000 joint), each extra dollar can make another 85 cents of benefits taxable, until 85% of them are. In that range a converted dollar adds up to $1.85 of taxable income.
The senior deduction shrinks
From 2025 through 2028, each person 65 or older can deduct an extra $6,000. It shrinks by 6 cents for every dollar of modified adjusted gross income over $75,000 ($150,000 joint), for each person who qualifies.
Medicare premiums can jump two years later
Medicare surcharges (IRMAA) start when modified adjusted gross income passes $109,000 ($218,000 joint) in 2026, and they are based on the tax return from two years earlier. One dollar over a threshold costs the full surcharge for the year. See the 2026 IRMAA brackets.
Limits
What this calculator doesn’t cover
- State income tax.
- Capital gains and qualified dividends, which a conversion can push from the 0% rate to 15%, and the 3.8% net investment income tax.
- Tax-exempt interest, which counts toward Social Security taxation and IRMAA.
- Itemized deductions, and filing statuses other than single and married filing jointly.
- Health insurance subsidies before 65: a conversion can reduce Affordable Care Act premium tax credits.
- After-tax (nondeductible) money in your IRAs, which makes part of a conversion tax-free.
Questions
Frequently asked questions
- How is a Roth conversion taxed?
- The amount you move from a traditional IRA or pre-tax workplace plan to a Roth is added to your ordinary income for the year and taxed at your regular federal rates. The conversion itself has no 10% early-withdrawal penalty.
- Can a Roth conversion make my Social Security taxable?
- Yes. Up to 85% of your benefits can be taxed. Until you reach that cap, each extra dollar of income can make another 50 or 85 cents of benefits taxable, so a conversion can cost more than your tax bracket suggests.
- How does the new senior deduction affect a conversion?
- From 2025 through 2028, each person 65 or older can deduct an extra $6,000. It shrinks by 6% of modified adjusted gross income over $75,000 ($150,000 on a joint return), so in that range each converted dollar also removes 6 cents of deduction for each person who qualifies.
- Will a Roth conversion raise my Medicare premiums?
- It can, two years later. Medicare surcharges (IRMAA) for 2028 will be based on your 2026 modified adjusted gross income, which includes the conversion. Going $1 over a threshold means the full surcharge for that tier.
- What is the deadline for a 2026 Roth conversion?
- December 31, 2026. Unlike IRA contributions, a conversion counts in the year the money leaves the traditional account, and since 2018 a conversion can no longer be undone.
- Should I pay the tax from the IRA or from other savings?
- Paying from other savings keeps the whole converted amount growing tax-free in the Roth. Tax withheld from the conversion is a regular withdrawal: it never reaches the Roth, and if you are under 59½ it can also owe the 10% penalty.
Plan conversions across the years
One year is a start. Velafolio’s free planner models conversions over the years you choose and compares lifetime taxes and what you leave behind against not converting.