The next dollar
At $40,000 of ordinary income, one more dollar costs you 22.2 cents. The tax table says 12%.
The Real Rate
Drag across the chart to read any income.
- What the next dollar costs
- What the tax table says
- Social Security torpedo
- Medicare IRMAA cliff
Every step of the computation
at $40,000 of ordinary income
What this is, and what it is not
A calculator, not advice
MARGINAL computes and displays. It does not recommend an action, and nothing here is tax, legal or investment advice. Check any figure that matters with a professional who has seen your whole return.
What is modelled
United States federal income tax for a single filer in tax year 2026: the ordinary brackets, long-term capital gains stacked on top of ordinary income, taxation of Social Security benefits, the standard deduction with the age-65 addition and the temporary senior bonus deduction with its phase-out, Medicare Part B IRMAA, and required minimum distributions.
What is not modelled
State income tax. The alternative minimum tax. The net investment income tax. Medicare Part D IRMAA. ACA premium subsidies before 65. The widow's penalty. Qualified charitable distributions. Cost basis in taxable accounts. Itemised deductions. The IRMAA two-year lookback, which this single-year view approximates by using this year's own income.
Where the numbers come from
Every constant is taken from the IRS inflation adjustments for 2026, IRS Publications 915 and 590-B, and the CMS Medicare premium notice, and is listed with its source in the project's audit file. Known discrepancies are recorded there rather than hidden.