Pre-tax deductions exempt from FICA are the ones that flow through a Section 125 cafeteria plan: your share of employer-sponsored health, dental, and vision premiums; HSA contributions made through payroll; health care FSAs; and dependent care FSAs within the annual limit. These shrink your wages for income tax, Social Security, and Medicare at once. Traditional and Roth 401(k) contributions do not — they lower your income tax wages but stay fully subject to FICA.
The Deductions That Actually Reduce FICA Wages
What ties the FICA-exempt deductions together is the cafeteria plan. IRC Section 3121(a)(5)(G) excludes qualifying cafeteria plan benefits from the definition of “wages,” so the salary reduction never becomes wages for FICA to attach to. The IRS has stated that salary reduction contributions to a Section 125 plan “are not actually or constructively received by the participant” and “generally are not subject to FICA and FUTA.”
Health, Dental, and Vision Premiums
Your share of employer-sponsored health, dental, and vision premiums is the most common FICA-exempt deduction. When your employer runs the premium through a Section 125 plan, those dollars never count as wages for income tax or FICA. For most workers with employer coverage, this happens automatically — the premium disappears from gross pay before any tax is calculated.
HSA Contributions Through Payroll
HSA contributions made through your employer’s payroll avoid federal income tax, Social Security tax, and Medicare tax at the moment of contribution. For 2026, the contribution ceiling is $4,400 with self-only high-deductible coverage and $8,750 with family coverage. The FICA exemption only applies when the money moves through payroll. If you fund your HSA directly from a bank account instead, you can still deduct the amount on your return for income tax, but you cannot recover the FICA already withheld on those earnings.
Health Care FSAs
A health care FSA (sometimes called a medical FSA) offered through a Section 125 plan is FICA-exempt. Dollars you set aside for copays, prescriptions, and other qualified medical expenses come out before income tax and FICA. The 2026 employee contribution maximum is $3,400.
Dependent Care FSAs
Dependent care FSA contributions through a cafeteria plan are also exempt from FICA. This one trips up even some payroll professionals, who occasionally treat dependent care contributions as FICA-taxable by mistake. The IRS has confirmed that cafeteria plan dependent care assistance is generally not subject to FICA. For 2026, the household maximum is $7,500, or $3,750 for married individuals filing separately. Amounts above the annual limit have to be added back into both income tax wages and FICA wages.
Why 401(k) Contributions Still Owe FICA
This is the piece most people get wrong. Traditional 401(k) elective deferrals lower your income tax wages but remain fully subject to Social Security and Medicare taxes. The IRS is explicit: pre-tax employee salary deferrals to 401(k), 403(b), and governmental 457(b) plans are subject to FICA withholding. Roth 401(k) contributions owe both income tax and FICA.
The reason is structural. Congress wrote a specific cafeteria plan carve-out into Section 3121(a)(5)(G); it never wrote an equivalent one for employee retirement plan deferrals. Employer matching contributions to the plan trust are excluded from FICA wages under a different provision, but your own elective deferrals are not. For 2026, the elective deferral limit is $24,500, and every dollar of it owes Social Security and Medicare tax.
Other Benefits With Their Own FICA Rules
A few benefits sit outside the clean exempt/not-exempt split and deserve their own look.
Group-Term Life Insurance Above $50,000
Employer-provided group-term life insurance is tax-free on the first $50,000 of coverage. Beyond that, the cost of the excess coverage becomes imputed income and owes Social Security and Medicare taxes even though you receive no cash. Your employer calculates the amount from an IRS premium table, adds it to your FICA wage base, and reports it on your W-2 in Box 12 with Code C. You may notice a small FICA deduction on your pay stub that corresponds to this benefit.
Adoption Assistance
Employer-provided adoption assistance up to $17,670 in 2026 is excluded from federal income tax, but the full amount still owes Social Security and Medicare taxes. You pay FICA on money that never shows up as taxable income on your return.
Qualified Transportation Benefits
Employer-provided transit passes, vanpool benefits, and qualified parking can be excluded from income tax wages up to $340 per month for transit and $340 per month for parking in 2026. These benefits are usually provided directly rather than through salary reduction, though some employers run them as pre-tax payroll deductions. FICA treatment depends on how the benefit is structured and whether it qualifies as de minimis. If you receive transit or parking benefits and want to confirm whether they are reducing your FICA wages, ask your payroll department.
Checking the Treatment on Your W-2
Your W-2 shows exactly which deductions reduced your FICA wages. Box 1 reports federal taxable wages. Box 3 reports Social Security wages. Box 5 reports Medicare wages. A FICA-exempt deduction lowers all three boxes. A deduction that only reduces income tax lowers Box 1 but leaves Boxes 3 and 5 alone.
A concrete example. You earn $80,000, contribute $5,000 to a traditional 401(k), and pay $3,000 toward health insurance premiums through a Section 125 plan. Box 1 drops by $8,000 to $72,000, because both deductions reduce income tax wages. Boxes 3 and 5 drop by only $3,000 to $77,000, because the 401(k) deferral stays in the FICA wage base.
That is the normal pattern: Boxes 3 and 5 run higher than Box 1 for anyone contributing to a 401(k) or similar plan. If Box 1 is instead higher than Boxes 3 and 5, something unusual is happening and it is worth raising with payroll. Box 12 fills in the detail. Code D flags 401(k) deferrals, Code E flags 403(b) deferrals, Code G flags 457(b) deferrals, and Code W flags employer and employee HSA contributions. Cross-checking these codes against your box totals is the most reliable way to verify each deduction got the treatment you expected.
The Trade-off Behind FICA-Exempt Benefits
One thing to keep in mind as you load up on Section 125 benefits: dollars that bypass FICA do not count toward your Social Security earnings record. The payroll tax savings are immediate and real, but over a long career of maximizing cafeteria plan deductions, the cumulative reduction in your recorded earnings can slightly lower your eventual monthly Social Security benefit. For most people the current savings outweigh the future effect. It is still a trade-off, and worth knowing about before you assume FICA-exempt is pure upside.