Raising a pre-tax deduction lowers take-home by less than the full amount, because it cuts your taxes too.
This calculator shows how raising a pre-tax deduction lowers your take-home pay by less than the full amount because it also cuts your taxes.
A pre-tax deduction, such as a retirement or health contribution, comes out of your pay before taxes are calculated. That lowers your taxable wages, so part of the increase is offset by the taxes you no longer owe. As a result, adding a given amount to the deduction reduces your paycheck by less than that amount.
The calculator multiplies your deduction increase by your combined tax rate to find the tax savings, then subtracts that from the increase to show the real hit to take-home. This makes it easier to decide how much more you can afford to contribute. It uses a single combined rate as an approximation and is not tax advice, so your actual paycheck may vary with your full withholding setup.
Because the deduction is pre-tax, it lowers the income you are taxed on. The taxes you save cover part of the contribution, so your paycheck drops by less.
Common examples include traditional 401(k), 403(b), or 457(b) contributions and many health or flexible-spending plan premiums. Roth contributions are after-tax and would not create this effect.
Use your combined marginal rate, roughly your federal, state, and payroll taxes on the next dollar. This is an estimate and not a substitute for professional tax advice.
See the exact formula and a worked example on our methodology page.