Calculators · Tax year 2026
Free federal tax calculators
Each tool shows its work, names the code section behind every line, and ships a disclaimer next to the result — not buried in a footer. Nothing is sent anywhere unless you choose to save a result.
- 01Estimated tax after selling stockWhat a stock sale actually adds to your tax bill this year — income tax, NIIT, and your balance due at filing.
- 02RSU withholding gapThe difference between the 22% your broker withholds at vest and the true tax once the vest stacks on your salary.
- 03Underpayment penalty & safe harborWhether you're on track to clear the §6654 safe harbors, and a proxy for the penalty if you fall short.