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By Jamie Reeves, Personal Finance Writer

Which Paycheck Deductions Are Pre-Tax? (Pre-Tax vs After-Tax)

A paycheck splitting into a pre-tax stack that shrinks the taxable slice and an after-tax stack that does not

Pre-tax deductions come out of your gross pay before income tax is calculated — and, for some of them, before Social Security and Medicare too — which lowers the wages you get taxed on and shrinks your tax bill. The big pre-tax items are traditional 401(k) contributions, HSA and FSA contributions, and most employer health, dental, and vision premiums (run through a Section 125 “cafeteria” plan), plus qualified commuter benefits. After-tax deductions come out after taxes are figured and give you no break on taxable income: Roth 401(k) contributions, wage garnishments, union dues, and after-tax insurance. The practical rule: a pre-tax dollar costs you less than a dollar of take-home pay; an after-tax dollar costs you the full dollar.

“Is this pre-tax?” is one of the most useful questions you can ask about any paycheck deduction, because the answer changes what the deduction actually costs you. Below is the full list on each side, the one nuance that trips almost everyone up (401(k) and FICA), and how to read which is which straight off your pay stub.

What “Pre-Tax” Actually Does

Your paycheck is processed in layers. Gross pay comes first; then pre-tax deductions are subtracted to arrive at your taxable wages; then taxes are calculated on that smaller number; then after-tax deductions come out. A pre-tax deduction wins twice over an after-tax one of the same size: you avoid tax on the money now, and your paycheck drops by less than the full amount because part of the “cost” is tax you would have paid anyway. For the full order of operations, see how to read a pay stub and gross pay vs net pay.

The Pre-Tax List

  • Traditional 401(k), 403(b), 457. Reduce federal (and usually state) income tax. 2026 elective deferral limit is $24,500 per the IRS. Still subject to FICA (see the nuance below).
  • HSA contributions via payroll. Exempt from income tax and FICA when made through a Section 125 plan. See HSA vs FSA.
  • FSA (health and dependent care). Pre-tax for income tax and FICA; use-it-or-lose-it rules apply.
  • Section 125 insurance premiums. Employer medical, dental, and vision premiums, when offered through a cafeteria plan, are exempt from income tax and FICA per IRS Publication 15-B.
  • Qualified commuter / transit benefits. Pre-tax up to the monthly IRS limit for transit and parking.

The After-Tax List

  • Roth 401(k) / Roth IRA — taxed now, tax-free in retirement.
  • Wage garnishments — court-ordered, taken from after-tax pay. See how much of my paycheck can be garnished.
  • Union dues and association fees.
  • After-tax insurance — some disability and life coverage (paying after-tax can make disability benefits tax-free).
  • Charitable payroll deductions.

The Nuance Everyone Misses: 401(k) vs FICA

Not all pre-tax deductions are pre-tax for the same taxes. A traditional 401(k) contribution is excluded from your federal income tax wages (W-2 Box 1), so it cuts your income tax — but it is still counted in your Social Security and Medicare wages (Boxes 3 and 5), so you pay the full 7.65% FICA on it (per IRS Topic 751). HSA, FSA, and Section 125 premiums are the deductions that dodge FICA too. That extra 7.65% is exactly why an HSA earns its “triple tax advantage” reputation.

Which Taxes Each Deduction Escapes

DeductionPre- or after-taxCuts income tax?Cuts FICA?
Traditional 401(k) / 403(b)Pre-taxYesNo
HSA (via payroll)Pre-taxYesYes
FSA (health / dependent care)Pre-taxYesYes
Health / dental / vision (Section 125)Pre-taxYesYes
Qualified commuter / transitPre-taxYesYes
Roth 401(k)After-taxNoNo
Wage garnishmentAfter-taxNoNo
Union duesAfter-taxNoNo

What Pre-Tax Actually Saves You

Your savings equal the deduction times your combined marginal rate. Say you are a single filer earning $70,000 in the 22% federal bracket:

  • $200/paycheck into a traditional 401(k) saves ~$44 in federal income tax (22% × $200) but nothing on FICA — so your take-home drops by about $156, not $200.
  • $200/paycheck into an HSA saves ~$44 income tax plus~$15 FICA (7.65%) — about $59 total — so take-home drops by only ~$141.

Same $200, different tax treatment, different real cost. To see the whole gross-to-net picture with your own numbers, run the take-home pay calculator, and for how the tax lines themselves work, see how much taxes are taken out of my paycheck. If you are weighing the pre-tax-now vs tax-free-later trade, our Roth vs traditional 401(k) breakdown runs the math both ways.

How to Tell on Your Pay Stub

Pre-tax deductions almost always appear above the tax withholding lines (or in a section labeled “pre-tax” / “before-tax”), because they are subtracted before tax is computed. After-tax deductions sit belowthe tax lines. If a deduction is lowering the “taxable gross” figure on your stub, it is pre-tax; if it comes off the bottom after taxes, it is after-tax. When in doubt, compare your gross to the “federal taxable wages” box: the gap is your total pre-tax deductions.

Sources and Methodology

401(k) and retirement contribution limits: IRS retirement contribution limits. Cafeteria plans and fringe-benefit tax treatment: IRS Publication 15-B (Employer’s Tax Guide to Fringe Benefits). FICA (Social Security and Medicare) rules: IRS Topic 751. HSA rules: IRS Publication 969. Savings figures use 2026 federal brackets and the 7.65% combined FICA rate. General information, not tax advice; your plan documents govern. Last updated July 25, 2026.

Frequently Asked Questions

A pre-tax deduction is money taken out of your gross pay before taxes are calculated, which lowers the wages you get taxed on. Because the deduction reduces your taxable income, you never pay income tax on that money (and, for some benefits, no Social Security or Medicare tax either). The result is that a pre-tax dollar 'costs' you less than a dollar of take-home pay — if you are in the 22% bracket, a $100 pre-tax 401(k) contribution reduces your paycheck by only about $78. After-tax deductions, by contrast, come out after taxes are figured and give you no such break.
The common pre-tax deductions are: traditional 401(k), 403(b), and 457 retirement contributions; Health Savings Account (HSA) contributions made through payroll; Flexible Spending Account (FSA) contributions for health or dependent care; employer medical, dental, and vision insurance premiums run through a Section 125 'cafeteria' plan; and qualified commuter/transit benefits. These reduce the wages your income tax is calculated on. A key split: 401(k) contributions lower income tax but are still subject to Social Security and Medicare (FICA), while HSA, FSA, and Section 125 premiums are exempt from both income tax and FICA.
No. This is the most common misunderstanding about pre-tax deductions. A traditional 401(k) contribution is excluded from your federal income tax wages (W-2 Box 1), so it lowers your income tax — but it is still included in your Social Security and Medicare wages (Boxes 3 and 5), so you pay the full 7.65% FICA on it. HSA and FSA contributions made through a cafeteria plan, and Section 125 insurance premiums, are the deductions that escape FICA too. That FICA difference is why an HSA is sometimes called 'triple tax-advantaged.'
After-tax (post-tax) deductions come out of your pay after all taxes are calculated, so they do not reduce your taxable income. The main ones are: Roth 401(k) and Roth IRA contributions, court-ordered wage garnishments, union dues, after-tax disability or life insurance premiums, and charitable payroll deductions. You have already paid income tax and FICA on this money. The trade-off for a Roth is on the other end — qualified Roth withdrawals in retirement come out tax-free.
Your savings equal the deduction multiplied by your combined marginal tax rate. For income-tax-only pre-tax items like a 401(k), that is your federal (and state) income tax rate: a $200 contribution in the 22% federal bracket saves about $44 in federal tax. For FICA-exempt items like an HSA or Section 125 premium, add 7.65% for Social Security and Medicare: the same $200 would save about $59. Over a year, maxing pre-tax benefits can cut a middle-income worker's tax bill by thousands — which is the entire point of offering them through payroll.
A Roth 401(k) is after-tax. Contributions come out of your paycheck after income tax has been withheld, so they do not lower your current taxable income the way a traditional 401(k) does. The benefit is deferred: qualified withdrawals in retirement — including all the investment growth — are tax-free. A traditional 401(k) is the opposite: pre-tax now, taxed on withdrawal. Which is better depends mainly on whether your tax rate is higher today or expected to be higher in retirement.
Usually yes, if your employer offers them through a Section 125 cafeteria plan — which most do. In that case your medical, dental, and vision premiums are deducted before income tax and before FICA, so they lower both. If you buy coverage outside an employer plan (for example, on the individual marketplace and paid from your own pocket), those premiums are not a pre-tax payroll deduction, though they may be deductible elsewhere on your tax return. Check your pay stub: pre-tax premiums typically appear above the tax lines, after-tax ones below.

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