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HSA vs FSA

One account is yours forever. The other evaporates. See the dollar difference on YOUR numbers.

Both accounts pay medical bills with pre-tax money — but an HSA is a permanent, investable, triple-tax-free asset while a health FSA is a year-long coupon with a $680 carryover at most. The right comparison is not "which saves more this year" (both save your marginal rate, plus 7.65% FICA when payroll-deducted) but what happens to the money you don't spend: HSA leftovers roll over and compound for decades, FSA leftovers above the carryover are forfeited. This calculator prices both sides with 2026 limits and your actual tax rates.

Why people use this

Employees at open enrollment use it to end the debate with their own numbers: both accounts save the same marginal rate, but the HSA leftover compounds for decades while the FSA forfeits everything above the $680 carryover — plus the spouse-FSA trap that silently kills HSA eligibility.

How it works

1. Tax savings = contribution × (federal + state + 7.65% FICA if payroll-deducted). Direct HSA contributions skip the FICA piece.
2. HSA: contribute the max ($4,400 self / $8,750 family for 2026, +$1,000 at 55+), spend what you need, and the leftover compounds at your growth rate — tax-free going in, growing, and coming out for medical.
3. FSA: contribution capped at $3,400, forfeiture = contribution − spending − $680 carryover (if the plan allows carryover at all — some offer only a 2½-month grace period, some neither).
4. Eligibility: the HSA requires an HDHP (2026 minimum deductible $1,700 self / $3,400 family). A general-purpose FSA — even your spouse's — disqualifies HSA contributions; a limited-purpose dental/vision FSA does not.

Common questions

Family coverage, $3,000 of medical spending, 24% federal + 5% state. What is each account worth?

Maxing the HSA at $8,750 saves $3,207 in year one (including 7.65% FICA via payroll), and the $5,750 you didn't spend keeps compounding — $22,251 in 20 years at 7%, all tax-free for medical use. The FSA at $3,400 saves $1,246 with zero forfeiture. Same spending; the HSA is worth roughly $19,700 more over two decades.

How much FSA money do people actually forfeit?

Whatever exceeds spending plus the carryover. Elect $3,400, spend $2,000, and even with the 2026 maximum $680 carryover you forfeit $720 — more than half the tax you saved ($1,246 at the example rates), cutting the net benefit to $526. Plans without carryover forfeit the full $1,400. Elect only what you are certain to spend.

Can I have both an HSA and an FSA?

Only a limited-purpose FSA (dental and vision) — a general-purpose health FSA makes you HSA-ineligible, and your SPOUSE's general FSA counts too, the most common accidental disqualification. Two more traps: California and New Jersey tax HSA contributions at the state level, and the FSA's uniform-coverage rule lets you spend the full election on day 1 even before payroll has funded it — free float if you leave the job mid-year.

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