Traditional 401(k) contributions
Eligible traditional 401(k) employee deferrals generally reduce wages subject to federal income-tax withholding, but they generally remain subject to Social Security and Medicare taxes. The exact treatment depends on the plan and contribution type.
Roth 401(k) contributions
Designated Roth contributions are made after current federal income-tax withholding. They still reduce take-home cash because payroll sends the contribution to the retirement plan.
Limits and employer matches
This calculator does not determine eligibility, contribution limits, catch-up rules, plan compensation definitions or employer matching. Confirm those details with the plan administrator and current IRS guidance.
401(k) paycheck example
For a $65,000 salary paid biweekly, a 5% contribution equals $125 per paycheck before payroll rounding. A traditional contribution may lower federal taxable wages, while a Roth contribution is modeled after current income-tax withholding.
Frequently asked questions
Does a traditional 401(k) reduce Social Security and Medicare wages?
Employee elective deferrals generally remain subject to Social Security and Medicare taxes even when they reduce wages subject to federal income-tax withholding.
Does a Roth 401(k) lower current taxable income?
Designated Roth contributions are generally included in current gross income and are modeled as after-tax deductions here.