HSA and health FSA contributions made through payroll reduce your federal income tax, most state income taxes, AND FICA taxes — because they flow through a Section 125 cafeteria plan. This is more tax-efficient than a traditional 401(k), which skips FICA. For 2026, HSA limits are $4,400 (self-only) and $8,750 (family), with a $1,000 catch-up at age 55+ (Rev. Proc. 2025-19). The health FSA limit is $3,400 (Rev. Proc. 2025-32).
At $60,000 salary, contributing the full HSA self-only amount ($4,400) saves roughly $865 in federal taxes — $528 in income tax and $337 in FICA. Your paycheck drops by $3,535, not $4,400.
Use the paycheck calculator to model your HSA or FSA contribution alongside your full paycheck.
HSA vs. FSA: Key Differences
| Feature | HSA | Health FSA |
|---|---|---|
| 2026 limit (self-only) | $4,400 | $3,400 |
| 2026 limit (family) | $8,750 | $3,400 |
| Catch-up (55+) | +$1,000 | None |
| Eligibility requirement | Must be enrolled in HDHP | Any group health plan (varies) |
| Rollover | Unlimited — balance carries forever | Use-it-or-lose-it (limited rollover option) |
| Investment option | Yes — balance can be invested | No |
| Reduces FICA (via payroll) | Yes | Yes |
| Reduces income tax | Yes | Yes |
| Portable (leave job) | Yes | No — balance typically forfeited |
2026 HSA Limits
| Coverage | Base Limit | Catch-up (age 55+) | Maximum |
|---|---|---|---|
| Self-only | $4,400 | $1,000 | $5,400 |
| Family | $8,750 | $1,000 | $9,750 |
The $1,000 catch-up is set by statute (IRC §223(b)(3)) and is not indexed — it has not changed. The base amounts were set by Rev. Proc. 2025-19. To qualify for HSA contributions, you must be enrolled in a High Deductible Health Plan (HDHP) and not covered by any other non-HDHP health insurance, Medicare, or a non-limited FSA.
Worked Example: HSA Self-Only on a $60,000 Salary
Single filer, biweekly payroll, standard deduction, no state income tax.
| No HSA | HSA $4,400/yr (via payroll) | |
|---|---|---|
| Annual gross | $60,000 | $60,000 |
| HSA contribution (Section 125) | — | $4,400 |
| FICA wages | $60,000 | $55,600 |
| FICA tax (7.65%) | $4,590 | $4,253 |
| Federal taxable wages | $43,900 | $39,500 |
| Federal income tax | $5,020 | $4,492 |
| Annual take-home | $50,390 | $46,855 |
| Reduction in take-home | — | $3,535 |
| Per-biweekly-paycheck change | — | −$136 |
| Total tax savings | — | $865 |
Breakdown of $865 savings:
- Federal income tax: $5,020 − $4,492 = $528
- FICA: $4,590 − $4,253 = $337
You contribute $4,400 per year but your paycheck drops by only $3,535 because you save $865 in taxes. The FICA saving ($337) is something a 401(k) would not provide.
Worked Example: Health FSA $3,400 on a $60,000 Salary
| No FSA | FSA $3,400/yr | |
|---|---|---|
| FICA wages | $60,000 | $56,600 |
| FICA tax (7.65%) | $4,590 | $4,330 |
| Federal taxable wages | $43,900 | $40,500 |
| Federal income tax | $5,020 | $4,612 |
| Annual take-home | $50,390 | $47,658 |
| Reduction in take-home | — | $2,732 |
| Total tax savings | — | $668 |
Contributing $3,400 to a health FSA reduces take-home by $2,732 (saving $668 in taxes). If you have predictable medical expenses — copays, prescriptions, glasses, dental work — the FSA converts those after-tax costs to pre-tax ones.
Comparing HSA, FSA, and 401(k) Tax Savings
| Account | 2026 Limit | Reduces FICA? | Reduces Income Tax? | Rollover |
|---|---|---|---|---|
| HSA (self-only, payroll) | $4,400 | Yes | Yes | Yes |
| Health FSA (payroll) | $3,400 | Yes | Yes | No (limited) |
| Traditional 401(k) | $24,500 | No | Yes | Yes (invested) |
At the same dollar amount, HSA and FSA save more in total taxes than a 401(k) because they also reduce FICA. The difference is the HSA/FSA savings are locked to health spending (or future medical costs in the case of an invested HSA), while 401(k) money can be used for any purpose in retirement.
Stacking HSA and 401(k) Together
You can contribute to both an HSA (or FSA) and a traditional 401(k) simultaneously, subject to each account’s limits. Stacking them reduces both your income tax and your FICA base.
Example — $60,000 salary, HSA $4,400 + traditional 401(k) $6,000:
- FICA wages: $60,000 − $4,400 (HSA) = $55,600 (401k does not reduce FICA)
- FICA tax: $55,600 × 7.65% = $4,253
- Federal AGI: $60,000 − $4,400 − $6,000 = $49,600
- Taxable: $49,600 − $16,100 = $33,500
- Federal income tax: $1,240 + ($33,500 − $12,400) × 12% = $1,240 + $2,532 = $3,772
Compared to no contributions (tax $9,610), total tax with both accounts is $4,253 + $3,772 = $8,025 — a combined savings of $1,585. Of that savings, $337 comes from FICA (from the HSA), and the rest comes from income tax reductions across both accounts.
What the FSA Use-It-or-Lose-It Rule Means
Health FSA funds must be used for qualifying medical expenses during the plan year. Employers may optionally offer:
- A grace period of up to 2.5 months after the plan year ends, OR
- A rollover of up to $660 (the 2026 limit, indexed) to the following year.
They cannot offer both. If your employer offers neither, unused funds are forfeited at year end. Budget conservatively — only contribute what you expect to spend on out-of-pocket medical, dental, and vision costs.
An HSA has no such restriction. Unused balances grow indefinitely and can be invested; many people use their HSA as a long-term medical savings account and pay current expenses out of pocket.
For how these accounts interact with your broader paycheck picture, see 401(k) contributions and take-home pay and Roth vs. traditional 401(k) paycheck.