Both accounts deliver the identical tax savings on the same contribution — the real difference between them is what happens to money left unspent at year-end.
How it works
Tax savings are computed identically for both accounts. The comparison is in what the unspent balance means: an FSA typically forfeits it (absent a limited employer grace period or rollover provision), while an HSA carries it forward indefinitely, growing tax-deferred for future use.
What this does not include
An HSA requires enrollment in a qualifying high-deductible health plan, which an FSA doesn’t — eligibility, not just the forfeiture rule, often decides which account is even available to a given person, a determination this calculator doesn’t make.
How to use this calculator
- Enter the annual contribution and expected unspent amount at year-end.
- Enter your combined marginal tax rate.
Frequently asked questions
Can I have both an FSA and an HSA?
Generally no for a standard health FSA — having one typically disqualifies HSA eligibility, though a “limited-purpose” FSA (covering only dental and vision) can be paired with an HSA.
Does an FSA always forfeit unspent funds?
Not entirely — many employer plans offer either a short grace period or a limited carryover amount, which softens but doesn’t eliminate the use-it-or-lose-it risk.
Why is an HSA often considered the better account when available?
The combination of tax-deductible contributions, tax-deferred growth, tax-free qualified withdrawals, and no forfeiture risk makes it the only triple-tax-advantaged account most people have access to.
