Roth Conversion Calculator 2026

Enter your income and a conversion amount to see the tax cost and your remaining bracket room instantly — then read how conversions work and when they pay off.

Private by design. No SSN, no bank login, no IRS login, no payroll password. Runs in your browser. Educational estimate only.
Your situation
$
Wages, pensions, taxable Social Security, other withdrawals.
yrs
yrs
$
Pre-tax dollars moved from a Traditional IRA/401(k) to a Roth.
Cost of this conversion
Conversion tax cost
$6,800
Effective rate on converted $
17.0%
Marginal bracket before12.0%
Marginal bracket after12.0%
Total tax before$7,144
Total tax after conversion$13,944
MAGI after conversion$110,000
You have about $66,300 of room left in the 12.0% bracket. Converting up to that amount keeps every converted dollar taxed at 12.0% or less.
See the multi-year payoff
This tool shows one year's cost. The Lifetime Tax Savings tool models a whole conversion ladder — how filling your bracket for several years cuts lifetime tax and future RMDs.
Open the Lifetime Tax tool →

Understand your result

How a Roth conversion is taxed

When you convert, the dollars you move from a Traditional IRA or 401(k) are added to your taxable ordinary income for the year and taxed at your marginal rates — there's no early-withdrawal penalty on a conversion. In return, the money grows tax-free in the Roth, comes out tax-free in retirement, and is exempt from required minimum distributions during your lifetime.

The strategy most retirees use is bracket filling: in a low-income year, convert just enough to reach the top of your current bracket. Beyond the tax you pay now, watch two side effects this tool flags — IRMAA (higher Medicare premiums about two years later) and the 3.8% net investment income tax — both driven by the higher MAGI a conversion creates. Paying the conversion tax from outside the IRA (with cash) makes the strategy far more effective, because every dollar keeps growing in the Roth.

Worked example

A married couple, both 66, with $70,000 of income converts $40,000 in a low-income year before RMDs and Social Security start:

  • The $40,000 stacks on top of $70,000, mostly filling the 12% and 22% brackets
  • The tool shows the extra federal + state tax — the conversion tax cost
  • Dividing that by $40,000 gives the effective rate on the converted dollars — the number to compare against your expected future rate
  • If your future rate (with RMDs + Social Security) would be higher, converting now wins
Common mistakes to avoid
Frequently asked questions
How much tax will I pay to convert?
The converted amount is added to your ordinary income and taxed at your marginal rates. This tool shows the difference in your total tax with and without the conversion — the conversion tax cost.
What does 'filling the bracket' mean?
Converting just enough to reach the top of your current bracket without spilling into the next, higher one. The tool shows your remaining bracket room.
Can a conversion raise my Medicare premiums?
Yes — a conversion raises MAGI, which can trigger IRMAA surcharges on Part B/D about two years later. The tool flags this.
When is a Roth conversion best?
Usually in low-income years — early retirement before RMDs and Social Security — when your marginal rate is temporarily low.
Can I undo a Roth conversion?
No. Since 2018, conversions can't be recharacterized (reversed). Convert deliberately and don't over-convert late in the year.
Does a conversion count toward my RMD?
No. If you're 73+, you must take your RMD first; it can't be converted. Conversions reduce future RMDs by shrinking the pre-tax balance.
Sources & verification
Related calculators & guides
Lifetime Tax Savings Calculator
Model a multi-year conversion ladder
RMD Calculator 2026
See the RMDs conversions help you avoid
Roth vs Traditional IRA Calculator
Where new contributions should go
Educational estimate only. This uses a simplified 2026 federal model plus a flat state rate; it does not capture every interaction (Social Security taxation changes, ACA subsidies, capital-gain stacking, or exact IRMAA tiers). Confirm with a qualified tax professional before converting. Full disclaimer.