Take-Home Pay Calculator with 401(k), HSA, and FSA Deductions

How does a 401(k) contribution affect my take-home pay?

A traditional 401(k) contribution reduces your federal income taxable wages by the contribution amount, lowering the federal income tax withheld from your paycheck. It does not reduce Social Security or Medicare taxes. For a single filer in the 22% bracket, a $200 per-period contribution reduces federal withholding by approximately $44. Your net take-home decreases by $156, not the full $200, because of the tax offset.

Do health insurance premiums reduce Social Security and Medicare taxes?

Yes, if paid through an employer Section 125 cafeteria plan. Premiums under a Section 125 plan reduce both federal income taxable wages and FICA wages. That means Social Security at 6.2% and Medicare at 1.45% are both calculated on the lower amount. Premiums paid outside a cafeteria plan do not reduce FICA wages.

What is the difference between pre-tax and post-tax deductions?

Pre-tax deductions are subtracted from gross pay before taxes are calculated. They reduce taxable income and lower the taxes withheld. Traditional 401(k), health insurance under Section 125, FSA, and HSA are all pre-tax. Post-tax deductions are subtracted after all taxes are calculated. Roth 401(k) contributions are post-tax. They reduce net pay but do not reduce any taxes.

Does an HSA contribution through payroll reduce FICA taxes?

Yes. HSA contributions made through employer payroll are excluded from FICA wages under IRC Section 106. Social Security and Medicare are both calculated after the HSA amount is removed. HSA contributions made directly to your HSA custodian, outside of payroll, do not reduce FICA. They still reduce federal income tax through the Schedule 1 above-the-line deduction, but the FICA benefit requires routing through payroll.

Why is my actual take-home pay less than my salary minus taxes?

Because your paycheck includes deductions beyond taxes. Health insurance premiums, retirement contributions, FSA and HSA deductions, and dental/vision premiums are all separate from the tax lines. Together these can total $400 to $700 per biweekly period for an employee with a typical benefits package. This calculator separates each layer so you can see what is reducing your paycheck.

Does a Roth 401(k) reduce my taxes?

No. Roth 401(k) contributions are post-tax. Federal income tax, Social Security, and Medicare are all calculated before Roth contributions are deducted. Your taxable wages are not reduced. The Roth advantage is tax-free growth and distributions in retirement. If you want to increase current take-home pay by reducing withholding, switching to traditional 401(k) contributions achieves that.

What is the 401(k) contribution limit for 2025?

The 2025 employee 401(k) contribution limit is $23,500 for employees under age 50. Employees age 50 or older can contribute up to $31,000 using the $7,500 catch-up contribution. These limits apply to the combined total of traditional and Roth 401(k) contributions. Employer matching contributions are separate and do not count against the employee limit.

What is the FSA contribution limit for 2025?

The health FSA contribution limit for 2025 is $3,300. The dependent care FSA limit is $5,000 per household ($2,500 if married filing separately). Both are Section 125 deductions and reduce federal income taxable wages as well as FICA wages. The health FSA is subject to the use-it-or-lose-it rule, though employers may allow a carryover of up to $660 or a grace period.

Can I contribute to both a 401(k) and an HSA in the same year?

Yes. The 401(k) and HSA are separate accounts with separate contribution limits. Contributing to both is a common strategy for maximizing tax savings per paycheck. The 401(k) reduces federal income tax only. The HSA reduces both federal income tax and FICA when contributions are made through payroll. You must be enrolled in a high-deductible health plan to contribute to an HSA.