What Are Pre-Tax Deductions on My Paycheck? Types and Limits

Pre-tax deductions on your paycheck are amounts your employer subtracts from your gross pay before calculating federal income tax, state income tax, and in some cases Social Security and Medicare taxes. Shrinking the wages that get taxed leaves more money in your take-home pay. The most common categories are retirement plan contributions, health insurance premiums, health savings accounts, flexible spending accounts, and commuter benefits.

How Pre-Tax Deductions Lower Your Taxes

The math is simple. Your employer subtracts the pre-tax deduction from your gross pay first, then calculates tax withholding on the smaller remaining amount. Earn $5,000 in a pay period and contribute $500 to a traditional 401(k), and your federal income tax gets calculated on $4,500 instead of $5,000. The $500 isn’t tax-free forever. It gets taxed later, when you withdraw it in retirement. You just avoid paying tax on it right now.

Post-tax deductions run in the opposite direction. Your employer withholds taxes on the full $5,000, then subtracts the deduction from what’s left. Roth 401(k) contributions, wage garnishments, and most union dues are common post-tax items. The net effect is a smaller take-home pay compared to making the same dollar contribution pre-tax.

Pre-tax deductions also reduce your adjusted gross income, which is the number the IRS uses for eligibility on various tax credits and deductions. A lower AGI can keep you within income thresholds for benefits that phase out at higher levels.

Common Types You’ll See on a Pay Stub

Most pre-tax deductions fall into a handful of categories, each authorized by a different section of the tax code.

Retirement Plan Contributions

Contributions to a traditional 401(k), 403(b), or governmental 457(b) are the most recognizable pre-tax paycheck deductions. Your contribution is excluded from current taxable income and grows tax-deferred until you take withdrawals, at which point the money is taxed as ordinary income. For 2026, the employee elective deferral limit is $24,500.¹

If your employer offers a match, those matching dollars don’t count against your $24,500 limit. Employer contributions are also excluded from your current taxable income and aren’t subject to FICA taxes until distributed.

Health Insurance Premiums

The premiums you pay toward employer-sponsored health, dental, and vision coverage are usually the single largest pre-tax deduction on a paycheck. These premiums flow through a Section 125 cafeteria plan, which is the legal structure that lets your employer deduct them before calculating both income tax and payroll taxes.² Because Section 125 deductions also reduce your Social Security and Medicare wages, they save you more per dollar than a retirement contribution does on a paycheck-to-paycheck basis.

Health Savings Accounts

A health savings account is available only if you’re enrolled in a qualifying high-deductible health plan. HSAs get a triple tax advantage: contributions are pre-tax, the balance grows tax-free, and withdrawals for qualified medical expenses are tax-free. The account belongs to you, not your employer, so it follows you if you change jobs. For 2026, the contribution limit is $4,400 for self-only coverage and $8,750 for family coverage.³

Flexible Spending Accounts

A health care FSA lets you set aside pre-tax money for out-of-pocket medical costs like copays, prescriptions, and eyeglasses. For 2026, the maximum employee contribution is $3,400.⁴ Unlike an HSA, a health care FSA is generally use-it-or-lose-it. Unspent funds at the end of the plan year are forfeited, though some plans offer a grace period or a small carryover.

A dependent care FSA covers qualifying childcare or elder care expenses while you work. The annual limit is $7,500 per household, or $3,750 if you’re married and file a separate return.⁵ Both types of FSA run through a Section 125 plan, so contributions reduce your income tax and FICA tax.

Commuter Benefits

Qualified transportation fringe benefits cover mass transit passes, vanpool costs, and qualified parking. Your employer can let you pay for these expenses with pre-tax dollars under Section 132(f) of the tax code.⁶ For 2026, the monthly exclusion is $340 for transit and vanpool combined, plus a separate $340 for qualified parking.⁷

Group-Term Life Insurance

Your employer can provide up to $50,000 of group-term life insurance coverage tax-free. Coverage below that threshold doesn’t appear in your taxable wages at all. If your employer provides more, the cost of the excess is added back to your wages as imputed income, which is a line item you’ll see on your pay stub and W-2 even though you never received the money as cash.⁸ That imputed income is subject to Social Security and Medicare taxes.⁷

Not All Pre-Tax Deductions Cut FICA

This is where people get tripped up. FICA taxes fund Social Security (6.2% of wages up to the $184,500 wage base in 2026) and Medicare (1.45% of all wages, plus an additional 0.9% on wages above $200,000).⁹

Health insurance premiums, FSA contributions, and HSA contributions processed through a Section 125 cafeteria plan reduce your wages for both income tax and FICA. Every dollar you contribute saves you income tax plus the 7.65% FICA tax.²

Traditional 401(k) and 403(b) contributions work differently. They reduce your income for federal and state income tax, but the full contribution amount is still subject to Social Security and Medicare taxes. Your W-2 will show a lower number in Box 1 (wages for income tax) than in Boxes 3 and 5 (Social Security and Medicare wages).¹⁰

One tradeoff to know about: because Section 125 deductions reduce your Social Security wages, they also reduce the earnings the Social Security Administration uses to calculate your future benefits. For most workers, the immediate tax savings outweigh any reduction in future benefits, especially when the money goes into an HSA or FSA covering expenses you’d pay anyway. Retirement plan contributions don’t create this issue because they’re still subject to FICA.

2026 Contribution Limits

The IRS adjusts most pre-tax contribution limits annually for inflation. The key ceilings for 2026:

If you’re between 60 and 63, you can defer up to $35,750 total in 2026 ($24,500 plus the $11,250 enhanced catch-up).¹¹

When You Can Change Your Elections

Retirement plan contributions are the flexible ones. Most employers let you increase, decrease, or stop your 401(k) or 403(b) contributions at any time, subject to your company’s payroll processing schedule. You can dial your contribution rate up or down as your finances shift, as long as you don’t exceed the annual limit.

Health-related benefits are far more rigid. Elections for health insurance premiums, FSAs, and other Section 125 benefits are locked in for the plan year once you make them. The annual open enrollment window, typically held late in the calendar year, is your main chance to adjust coverage levels and contribution amounts for the following year.

Outside of open enrollment, you can only change these elections after a qualifying life event: getting married or divorced, having or adopting a child, losing other health coverage, or a change in your or your spouse’s employment that affects benefit eligibility.¹² You typically need to notify your plan administrator within 30 to 60 days of the event. Miss that window and you’re locked into your current elections until the next open enrollment.

Reading Your W-2 Against Your Pay Stub

Your year-end Form W-2 is where the pre-tax deductions on every paycheck are totaled up. Box 1 shows your wages after pre-tax deductions have been subtracted for income tax purposes. Boxes 3 and 5 show your Social Security and Medicare wages, which will be higher than Box 1 if you made traditional 401(k) contributions, because those contributions reduce income tax wages but not FICA wages.¹⁰

Box 12 breaks out specific pre-tax contributions using letter codes:¹³

Code D: traditional 401(k) elective deferrals
Code E: 403(b) salary reduction contributions
Code G: 457(b) elective deferrals
Code W: HSA contributions (both your payroll deductions and any employer contributions)
Code AA: designated Roth 401(k) contributions (post-tax, but reported here for tracking)

Compare these Box 12 amounts against your final pay stub for the year. If the numbers don’t match, contact your employer’s payroll department before filing your return. Catching a discrepancy in January is simple. Fixing it after the IRS flags a mismatch months later is not.

1
Internal Revenue Service. Retirement Topics – 401(k) and Profit-Sharing Plan Contribution Limits
2
Internal Revenue Service. FAQs for Government Entities Regarding Cafeteria Plans
3
HealthCare.gov. Understanding Health Savings Account-eligible Plans
4
Internal Revenue Service. Publication 15-B – Employer’s Tax Guide to Fringe Benefits
5
Office of the Law Revision Counsel. 26 USC 129 – Dependent Care Assistance Programs
6
Office of the Law Revision Counsel. 26 US Code 132 – Certain Fringe Benefits
7
Internal Revenue Service. Publication 15-B (2026), Employer’s Tax Guide to Fringe Benefits
8
Internal Revenue Service. Group-Term Life Insurance
9
Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates
10
Internal Revenue Service. Retirement Plan FAQs Regarding Contributions – Are Retirement Plan Contributions Subject to Withholding for FICA, Medicare or Federal Income Tax
11
Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500
12
HealthCare.gov. Qualifying Life Event
13
Internal Revenue Service. General Instructions for Forms W-2 and W-3