Estimate how 401(k), HSA, FSA, health premiums, commuter benefits, and other payroll deductions may affect taxes and monthly take-home pay.
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Filing, Pay and Location
Income and Withholding
W-4 Credits and Extra Withholding
Use the same common paycheck fields from Form W-4. Qualifying children are estimated at $2,000 each and other dependents at $500 each.
Retirement Contributions
If your employer match is calculated each paycheck, maxing out too early may cause you to miss matching contributions unless your plan has a true-up feature.
HSA, FSA and Pre-Tax Benefits
Only people covered by an eligible high-deductible health plan and meeting HSA eligibility rules may contribute to an HSA. Employer contributions count toward the annual HSA limit.
FSA elections may be subject to use-it-or-lose-it rules, carryover limits, grace periods, and employer plan terms.
After-Tax Paycheck Deductions
Use these for deductions that reduce take-home pay but usually do not reduce taxable wages, such as after-tax insurance, voluntary benefits, repayments, or other payroll deductions.
Take-Home Pay Target
Tax Treatment Notes
HSA payroll contributions may reduce federal income tax, state income tax, Social Security tax, and Medicare tax. Traditional 401(k) contributions generally reduce income tax but not Social Security or Medicare tax.
Traditional 401(k) contributions reduce federal taxable wages but generally do not reduce Medicare wages. Roth 401(k) contributions reduce take-home pay but do not reduce taxable wages.
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Contribution Summary
| Contribution | Planned | 2026 limit | Remaining | Tax treatment |
|---|
Tax Savings Summary
Detailed Outputs
Before relying on this estimate
Updated for 2026: federal tax brackets, standard deductions, Social Security wage base, and current 401(k), HSA, FSA, and commuter benefit limits used by this calculator.
This calculator provides a simplified planning estimate. It is not tax, legal, payroll, benefits, or investment advice. Actual results may differ based on employer plan rules, payroll timing, Form W-4 entries, withholding elections, credits, deductions, bonuses, other income, state and local treatment, HSA eligibility, FSA rules, and personal circumstances.
Use this result for paycheck planning
This estimate helps compare how traditional 401(k), Roth 401(k), HSA, FSA, insurance premiums, W-4 credits, extra withholding, commuter benefits, after-tax payroll deductions, and payroll taxes may affect average take-home pay. It is especially useful before benefits enrollment, open enrollment, a compensation change, or a planned increase in retirement or HSA contributions.
Why Your Paycheck Changes After 401(k), HSA, Insurance, W-4 Credits, and Extra Withholding
Your paycheck changes because different payroll items affect different parts of the calculation. Some reduce taxable wages, some reduce take-home pay only, and some change how much federal tax is withheld.
Pre-tax deductions can reduce taxable wages
Traditional 401(k) contributions, HSA payroll contributions, health FSA elections, dependent care FSA elections, medical insurance premiums, dental and vision premiums, commuter benefits, and other pre-tax payroll deductions may reduce the wages used for federal income tax. Some items, such as HSA payroll contributions and certain insurance premiums, may also reduce Social Security and Medicare wages.
Roth and after-tax deductions reduce take-home pay
Roth 401(k) contributions, after-tax insurance, voluntary benefits, repayments, and other after-tax payroll deductions generally reduce the amount deposited in your bank account, but they usually do not reduce current federal taxable wages.
W-4 credits and dependents can change withholding
Form W-4 allows employees to account for qualifying children, other dependents, and other tax credits. These entries can reduce federal withholding and increase estimated take-home pay, but the actual tax benefit depends on eligibility and the final tax return.
Extra withholding lowers take-home pay now
Extra federal withholding reduces each paycheck now. Some people use it to cover side income, investment income, a spouse’s income, or a prior-year tax bill so they are less likely to owe at filing time.
Final tax can still differ
The estimate can change if you have bonuses, irregular pay, spouse income, side income, investment income, state or local tax differences, credits, itemized deductions, or employer payroll rules that are not fully reflected in the entries.
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Example Take-Home Pay Planning Scenarios
These examples are simplified. Employer plan rules, payroll frequency, state treatment, and withholding elections can change the final paycheck result.
- $90,000 salary with traditional 401(k) contributions: increasing pre-tax 401(k) contributions may lower federal taxable wages while reducing take-home pay by less than the full contribution amount.
- HSA payroll contributions: eligible HSA contributions may reduce federal income tax and payroll-tax wages when made through payroll, which can make the paycheck effect different from a 401(k) contribution.
- Target take-home pay mode: use this mode to test how much pre-tax contribution room may remain while keeping monthly take-home pay above a chosen amount.
Frequently asked questions
Why can HSA contributions reduce taxes more than 401(k) contributions?
HSA payroll contributions may reduce federal income tax, state income tax in many cases, and payroll taxes. Traditional 401(k) contributions generally reduce income tax but not Social Security or Medicare wages.
Does Roth 401(k) reduce taxable income?
No. Roth 401(k) contributions are generally after-tax contributions, so they usually do not reduce current federal taxable income. They still reduce take-home pay because the contribution is withheld from the paycheck.
Does this calculator determine HSA eligibility?
No. It estimates payroll and tax effects based on the HSA eligibility choice entered by the user. HSA eligibility depends on high-deductible health plan coverage and other rules that this calculator does not fully verify.
Are state tax results exact?
No. State and local tax estimates are simplified unless a full state module is later added. State treatment of retirement contributions, HSA contributions, and other benefits may vary.
Should I use annual or per-paycheck amounts?
Use annual amounts unless the field says otherwise. The calculator is intended to estimate annual tax and paycheck effects, then translate those results into practical take-home pay comparisons.