About
HSA: triple tax advantage (deductible, growth tax-free, withdrawal tax-free for medical). 2026 limit $4,300 self / $8,550 family, plus a $1,000 catch-up at age 55+. Requires an HDHP. FSA: annual use-it-or-lose-it, 2026 limit $3,300 per employee, no HDHP needed. Both reduce taxable income in the year you contribute.
Formula
Frequently asked questions
Can I have both an HSA and an FSA at the same time?
Generally no, not a general-purpose FSA. The IRS treats a standard FSA as disqualifying coverage that blocks HSA contributions, because the FSA can pay first-dollar medical costs before the HDHP deductible is met. The exception is a limited-purpose FSA (LPFSA) restricted to dental and vision, or a post-deductible FSA. Those pair legally with an HSA, which is why many large employers offer an LPFSA alongside the HSA.
What happens to unused FSA money at the end of the year?
By default it is forfeited under the use-it-or-lose-it rule. Employers may offer one of two relief options, not both: a carryover of up to 660 dollars into the next plan year (the IRS indexes this figure), or a grace period of up to 2.5 months to spend the prior year balance. HSA money never expires; the full balance rolls over every year and stays yours even if you change jobs or insurers.
What are the 2026 HSA and FSA contribution limits?
For 2026 the HSA limit is 4,300 dollars for self-only HDHP coverage and 8,550 dollars for family coverage, with an extra 1,000 dollar catch-up for account holders age 55 and older. The health FSA limit is 3,300 dollars per employee. FSA limits are per employee, so a married couple can each contribute the full amount through their own employers.
Why is the HSA called triple tax-advantaged?
Three separate tax breaks stack: contributions are pre-tax or deductible so they lower taxable income, the balance grows tax-free whether invested or in cash, and qualified medical withdrawals are never taxed. No other US account combines all three. A 401(k) taxes withdrawals; a Roth taxes contributions. The FSA only delivers the first break, the up-front deduction.
Is an HSA better than an FSA for most people?
If you are eligible for an HSA (meaning you are enrolled in a qualifying HDHP), it is usually the stronger account because of rollover, investing, and portability. The FSA still wins in two cases: when you are not on an HDHP and cannot open an HSA at all, or when you have a large, certain near-term expense such as planned surgery or braces and want the full annual amount available on January 1.
HSA vs FSA: about these two accounts
A Health Savings Account (HSA) and a Flexible Spending Account (FSA) both let you pay medical costs with pre-tax dollars, but they behave very differently once the money is in. The HSA is an investment account you own for life; the FSA is an employer-owned spending account that mostly resets each year. Choosing between them is rarely about the size of the tax break in year one, because both shave the same amount off this year's taxable income. The real difference is what happens to the balance over time.
The HSA is the only account in the US tax code that is triple tax-advantaged. Contributions go in pre-tax or as a deduction, the balance grows tax-free whether you leave it in cash or invest it in funds, and withdrawals for qualified medical expenses are never taxed. Money you do not spend stays invested and compounds, which is why many savers treat a maxed-out HSA as a stealth retirement account. After age 65 you can withdraw HSA funds for any purpose and pay only ordinary income tax, exactly like a traditional 401(k).
The FSA delivers just the first of those three breaks: the up-front deduction. Its trade-off is timing. Your full annual election is available on day one of the plan year even though you have only contributed one paycheck's worth, so an FSA is useful when you know a large expense is coming. The catch is the use-it-or-lose-it rule: unspent money is generally forfeited at year end.
How the comparison works
This calculator models the long-run gap between the two accounts. The FSA only ever returns your annual tax saving, repeated each year. The HSA returns the same tax saving plus tax-free investment growth on every dollar you leave invested.
Annual tax saving = Contribution x Marginal tax rate FSA lifetime value = Annual tax saving x Years (no growth, balance resets) HSA balance = sum over each year of [ prior balance x (1 + return) + contribution ] HSA advantage = HSA balance - (FSA tax saving x Years)
- Contribution: capped at the 2026 limits below. The HDHP requirement applies only to the HSA.
- Marginal tax rate: the bracket your last dollar falls in. A 24 percent bracket means a 4,300 dollar HSA contribution cuts your tax bill by 1,032 dollars.
- Return: applies to the HSA only when you invest the balance rather than hold cash. The FSA cannot be invested.
Worked example
Take a household in the 24 percent federal bracket contributing 4,000 dollars per year for 20 years at a 7 percent invested return.
- Annual tax saving (both accounts): 4,000 x 0.24 = 960 dollars per year.
- FSA over 20 years: 960 x 20 = 19,200 dollars of tax savings, and nothing left in the account because each year resets.
- HSA balance after 20 years: 4,000 contributed annually and compounded at 7 percent grows to roughly 164,000 dollars.
- HSA growth on top of contributions: about 164,000 minus the 80,000 paid in, so roughly 84,000 dollars of tax-free gains the FSA can never produce.
2026 limits and feature comparison
| Feature | HSA | FSA |
|---|---|---|
| 2026 contribution limit | $4,300 self / $8,550 family | $3,300 per employee |
| Age 55+ catch-up | +$1,000 | None |
| Requires HDHP | Yes | No |
| Rolls over year to year | Yes, in full | No (carryover up to $660 or grace period) |
| Can be invested | Yes | No |
| Portable if you leave the job | Yes, you own it | No, employer owns it |
| Full amount available day one | No, funds as you contribute | Yes |
| Tax treatment | Triple (in, grow, out) | Single (in only) |
Common pitfalls
- Trying to run both at once. A general-purpose FSA disqualifies you from contributing to an HSA. Only a limited-purpose FSA (dental and vision) pairs legally with an HSA.
- Over-funding an FSA. Because unspent FSA money is forfeited, electing 3,000 dollars when you only spend 1,800 means donating 1,200 dollars back. Estimate conservatively.
- Treating the HSA as a checking account. Spending HSA dollars on every co-pay defeats the compounding advantage. If cash flow allows, pay small costs out of pocket and let the HSA invest.
- Missing the HDHP requirement. You can only open or contribute to an HSA while enrolled in a qualifying high-deductible health plan. Switch off the HDHP and contributions must stop.
- Forgetting receipts. The IRS lets you reimburse yourself years later for past qualified expenses, but only if you kept the receipts. Save them.