Pre-Tax Deductions Calculator (2026)
See how contributing to a 401(k), HSA, or FSA shrinks your taxable income — and how much of that contribution your take-home pay actually gives up after the tax savings.
By the Easy Guides Editorial Team · Updated for 2026
See exactly how much 401(k), HSA, FSA, and other pre-tax benefits lower your taxable income and change your take-home pay. Enter your details below (2026 tax figures) for a full per-paycheck and annual breakdown.
Enter 0 for no-tax states. Find your state rate →
Traditional (pre-tax) only. Typical range 3%–15%.
2026 limit: $4,300 single / $8,550 family.
2026 limit: $3,300.
Health, dental, vision premiums, transit, etc.
| Item | Without pre-tax | With pre-tax |
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Educational estimate only, not tax advice. Uses 2026 federal brackets and standard deductions, a 6.2% Social Security tax up to the $176,100 wage base, 1.45% Medicare, and a flat state rate you enter. Traditional 401(k) contributions reduce income tax but not FICA; HSA, FSA, and Section 125 premiums reduce both. Your real numbers depend on your W-4, employer plan, and state rules.
How pre-tax deductions actually work
A pre-tax deduction is money taken out of your gross pay before income tax is calculated. Because the government never sees that slice of your paycheck as taxable, your taxable income falls and your tax bill shrinks. The classic examples are a traditional 401(k) or 403(b), a Health Savings Account (HSA), a Flexible Spending Account (FSA), and most employer health, dental, and vision premiums.
The key insight is that a pre-tax contribution costs your take-home pay less than the amount you contribute. If you put $200 into a traditional 401(k) and you're in the 22% federal bracket, your paycheck only drops by about $156 — the other $44 would have gone to the IRS anyway. That's the tax savings this calculator makes visible.
Traditional 401(k) vs. Roth 401(k)
Only traditional (pre-tax) 401(k) contributions lower your taxable income today. You defer the tax and pay it when you withdraw in retirement. A Roth 401(k) is the opposite: you pay tax on the money now, but qualified withdrawals later are completely tax-free. Roth contributions do not reduce your current-year taxable income, so they won't show up as a tax savings here. Many people split contributions between the two to hedge against future tax rates.
The HSA triple tax advantage
An HSA (available if you have a qualifying high-deductible health plan) is the most tax-efficient account in the tax code. Contributions go in pre-tax, the money grows tax-free, and withdrawals for qualified medical expenses are also tax-free — three tax breaks in one. For 2026 you can contribute up to $4,300 (self-only) or $8,550 (family). Unlike an FSA, HSA balances roll over year to year and are yours to keep.
FSA: use it or lose it
A Flexible Spending Account also uses pre-tax dollars for medical (or dependent-care) costs, with a 2026 limit of $3,300 for health FSAs. The catch is the use-it-or-lose-it rule: most FSA money left unspent at the end of the plan year is forfeited, though some employers allow a small carryover or grace period. Fund it with expenses you know you'll have, like prescriptions, dental work, or glasses.
One important nuance the calculator handles for you: a traditional 401(k) reduces your income tax but is still subject to Social Security and Medicare (FICA) taxes. HSA, FSA, and Section 125 health premiums usually escape FICA too, so they save you a little more per dollar. Once you've set your contributions, check that your withholding still lines up using our W-4 withholding calculator.
Check your paycheck withholding
Pre-tax deductions change how much tax you owe — make sure your W-4 keeps up so you don't over- or under-withhold.
Open the W-4 calculator →