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Real Marginal Rate Calculator

2026 figures · reviewed September 5, 2026

Shows what one more withdrawal really costs in tax, once Social Security and Medicare react to it. About

In plain words. Your tax bracket says what rate the last dollar of income is taxed at. But in retirement one more dollar of income can also make more of your Social Security taxable, shrink a deduction, or push you into a higher Medicare premium tier. So the real cost of the next withdrawal is often much higher than the bracket. This tool computes that real rate on a withdrawal of any size, says what drove it, and draws the whole curve so you can see where it peaks.

Why it matters. Withdrawals and Roth conversions are sized against the real rate, not the printed one. Seeing the curve shows where a little more income costs a lot more tax, and where it stops.

An example. A single retiree with $30,000 of Social Security and $40,000 of other income is in the 22 percent bracket. The next $10,000 of IRA withdrawal costs about $1,680 in tax, 16.8 percent, because part of it fills a lower bracket; a little higher up the curve the rate passes 40 percent as the benefit is pulled into income.

Where it stops. It assumes ordinary income and the standard deduction. Capital gains and dividends sit in the same stack and shift the curve, and state tax adds to every point on it. Everything it leaves out.

$

Pensions, IRA withdrawals, wages, interest, and dividends. Everything on your tax return except Social Security.

Box 5 of each SSA-1099 in the household, added together.

The tool measures the real tax rate on this amount.

Filing status
Age

For a couple, answer for both spouses. At 65 the extra deductions and Medicare premiums come into play.

Real tax rate on the next $10,000
16.8%
Taking out that extra amount would cost $1,680 in federal income tax. The tax bracket printed for your income is 22%. The withdrawal also makes $3,150 more of your Social Security benefit taxable. It also cuts your senior deduction by $30.
Real tax rate on each extra $1,000 of other income, a single filer with $30,000 of Social Security, 2026A line from 0 to $250k of other income, showing the income tax rate on the next $1,000 at each point. It peaks at 35.0% near $249,000 and settles back toward the bracket rates once all of the benefit is taxable.0%10%20%30%40%50%$0$62k$125k$187k$249kYou: 16.8%
Income tax rate on the extra withdrawal
16.8%
$1,680 of tax on $10,000
Tax bracket you land in
22%
After the withdrawal
Highest real rate on the chart
35.0%
Reached near $249,000 of other income

Above two income lines, each extra dollar of other income makes 50 cents, then 85 cents, of your Social Security benefit taxable. So the bracket rate can apply to as much as $1.85 for every dollar you withdraw. The senior deduction shrinks by 6 cents for each dollar of income above $75,000. The Medicare premium tiers are cliffs, which is why the chart shows spikes. A withdrawal sized to stop just short of a tier line avoids the whole jump.

This uses the 2026 tax brackets, standard deduction, age-65 additions, and senior deduction, the federal rule for taxing Social Security benefits, and the Medicare premium tiers for each person on Medicare two years later. It treats all income as ordinary income with the standard deduction, and leaves out state tax, capital gains and qualified dividends, and other phase-outs. Educational, not advice.

This is a simplified model, not your actual tax return or plan. It only knows what you type in, leaves out rules that may apply to you, and cannot weigh the other facts and trade-offs a real decision depends on. Before you act, talk with a professional who knows your whole situation.

Educational only, not investment, tax, or legal advice. Results are hypothetical estimates that vary with each use and over time and are not guaranteed accurate or complete. Using this tool creates no client relationship with Considerate Capital, and the site that linked here is not affiliated with it. By using it you agree to the tool terms.