Flexible spending account contributions are not tax deductible, and that’s actually good news. Money you put into an FSA is excluded from your wages before payroll taxes are calculated, so it never becomes income you’d need to deduct later. The exclusion saves you more than a deduction would, because it also avoids Social Security and Medicare tax on every dollar you contribute.
Why an Exclusion Beats a Deduction
The legal basis for FSAs is Section 125 of the Internal Revenue Code, which governs what the IRS calls “cafeteria plans.” When you elect to redirect part of your salary into an FSA, that money is excluded from your gross income before taxes are calculated. You never receive it as wages, so there’s nothing to deduct later.1Office of the Law Revision Counsel. 26 U.S. Code 125 – Cafeteria Plans
The practical difference matters more than it sounds. A deduction reduces your taxable income when you file your return, but you still paid Social Security tax (6.2%) and Medicare tax (1.45%) on those wages throughout the year. An FSA exclusion removes the money before any of those calculations happen, so it also lowers your FICA tax bill. On a $3,400 health FSA contribution, that’s roughly an extra $260 in FICA savings you wouldn’t get from a deduction. Your employer saves its matching share of FICA too, which is one reason companies offer these plans.
Because the exclusion happens automatically through payroll, you don’t need to itemize deductions or do anything special on your tax return to capture the benefit. The savings show up in every paycheck as soon as contributions begin.
How Your FSA Shows Up on Your Tax Return
Health Care FSA
Your health FSA contributions are already excluded from the wages your employer reports on your W-2. The amount in Box 1 (federal taxable wages), Box 3 (Social Security wages), and Box 5 (Medicare wages) all reflect the reduction. You don’t claim an additional deduction, fill out an extra form, or list the money you spent from the FSA on Schedule A as a medical expense. If your health FSA is funded entirely through salary reduction, it won’t even appear in Box 12.2Internal Revenue Service. Form W-2 Reporting of Employer-Sponsored Health Coverage
Trying to also deduct expenses you paid for with FSA money would be double-dipping, and it’s the most common mistake people make. The tax benefit was already built into your paycheck.
Dependent Care FSA
Dependent care benefits work a little differently at filing time. They show up in Box 10 of your W-2, and you have to complete Part III of Form 2441 (Child and Dependent Care Expenses) to confirm the money went toward qualifying care. That form asks for each care provider’s name, address, and tax identification number. Missing or incorrect provider information can cause the IRS to treat those benefits as taxable income, which reverses the tax break entirely.3Internal Revenue Service. Child and Dependent Care Credit and Flexible Benefit Plans4Internal Revenue Service. Instructions for Form 2441 (2025)
Even though you’re filling out Form 2441, you’re not claiming a deduction on it. You’re documenting that the pre-tax benefit was used for qualified care. The dependent care tax credit and the dependent care FSA are separate mechanisms, and expenses paid through the FSA generally can’t be used again for the credit.
How Much You Can Shelter in 2026
The IRS caps how much can be excluded from wages each year, and those limits are adjusted for inflation.
For a health care FSA, the 2026 maximum salary reduction contribution is $3,400. That ceiling comes from Section 125(i), which set a base limit of $2,500 starting in 2013 and directs the IRS to adjust it for cost-of-living increases each year.1Office of the Law Revision Counsel. 26 U.S. Code 125 – Cafeteria Plans
For a dependent care FSA, the 2026 maximum household exclusion is $7,500 for joint, single, and head-of-household filers under the updated text of Section 129. If you’re married filing separately, the limit is $3,750.5Office of the Law Revision Counsel. 26 USC 129 – Dependent Care Assistance Programs This is a household limit, not a per-person limit. If both spouses have access to a dependent care FSA through their employers, combined contributions cannot exceed $7,500.
Whatever you contribute up to those limits comes out of federal income tax, state income tax in most states, Social Security tax, and Medicare tax. Every dollar of contribution is a dollar those four taxes never touch.
Who Can’t Use an FSA
FSAs are employer-sponsored plans. Self-employed individuals, sole proprietors, partners in a partnership, and anyone who owns more than 2% of an S corporation are not eligible to participate.6Internal Revenue Service. Publication 969 – Health Savings Accounts and Other Tax-Favored Health Plans If you’re in one of those groups and looking for a similar tax benefit on medical expenses, an HSA paired with a high-deductible health plan is the closest alternative. Self-employed individuals can also deduct health insurance premiums directly on their tax return, though that operates as an above-the-line deduction rather than a pre-tax exclusion, so it doesn’t save you FICA.
The One Cost of Taking the Pre-Tax Break
The same payroll tax savings that make FSAs attractive come with a downside most people never consider. Because your FSA contributions reduce your Social Security wages in Box 3, they also reduce the earnings the Social Security Administration uses to calculate your future retirement benefit. Every dollar that bypasses FICA is a dollar that doesn’t count toward your benefit formula.
For most people, the trade-off is minor. On a $3,400 health FSA contribution, the annual reduction in Social Security wages is small relative to a full career of earnings. If you’re in your highest-earning years, the period that most influences your benefit calculation, or if you’re close to one of the Social Security bend points where additional earnings have outsized value, it’s worth understanding what you’re giving up. The immediate tax savings almost always outweigh the marginal benefit reduction. But “almost always” isn’t “always,” and nobody should be surprised by it after the fact.