★ COMPARISONS · FSA VS HSA · TAX SAVINGS
The HSA wins by $1,146.50 — an FSA net value of $878.10 against an HSA value of $2,024.60. Put in the two contributions, your tax rates, the employer seed and what the FSA leaves unspent, and the calculator works out the tax savings on each side, what the FSA forfeits, and which account leaves you better off.
An FSA and an HSA both let you pay for medical costs with pre-tax money, but they work differently: the FSA is use-it-or-lose-it, the HSA rolls over and usually comes with an employer seed. This calculator puts the same tax rates on both and shows which one leaves you better off.
On the defaults — a $3,400 FSA contribution and a $4,400 HSA contribution, a 22% federal rate, a 5% state rate and 7.65% FICA, a $500 employer HSA seed and $300 left unspent in the FSA — the combined tax rate is 34.65%. The FSA tax savings are $1,178.10 ($3,400.00 × 34.65%), and after the $300.00 left unspent the FSA net value is $878.10. The HSA tax savings are $1,524.60 ($4,400.00 × 34.65%), and with the $500.00 employer seed the HSA value is $2,024.60. The HSA wins by $1,146.50. The two structural facts do the work: the HSA contribution is $1,000 larger, so it saves more tax, and the FSA forfeits $300 while the HSA keeps its seed.
Setup: FSA $3,400.00, HSA $4,400.00, federal 22%, state 5%, FICA 7.65%, employer seed $500.00, FSA unspent $300.00.
Line 1 — the combined rate. 22% + 5% + 7.65% = 34.65%.
Line 2 — the FSA tax savings. $3,400.00 × 34.65% = $1,178.10.
Line 3 — the FSA net value. $1,178.10 − $300.00 unspent = $878.10.
Line 4 — the HSA tax savings. $4,400.00 × 34.65% = $1,524.60.
Line 5 — the HSA value. $1,524.60 + $500.00 employer seed = $2,024.60.
Line 6 — the winner. $2,024.60 − $878.10 = $1,146.50 — the HSA wins. Rounding convention: figures are rounded to cents half-up, so rounded parts may differ by a cent from their rounded sum.
HSA family $8,750: FSA tax savings $1,178.10, FSA net value $878.10; HSA tax savings $3,031.88, HSA value $3,531.88; HSA wins by $2,653.78 A family HSA contribution of $8,750 nearly doubles the HSA tax savings, and the HSA wins by even more.
Employer seed $0: FSA tax savings $1,178.10, FSA net value $878.10; HSA tax savings $1,524.60, HSA value $1,524.60; HSA wins by $646.50 Without the employer seed the HSA still wins, but only by $646.50 — the seed is worth $500.00 of the $1,146.50 gap.
Unspent $0: FSA tax savings $1,178.10, FSA net value $1,178.10; HSA tax savings $1,524.60, HSA value $2,024.60; HSA wins by $846.50 Spending every FSA dollar lifts the FSA net value to the full tax savings, and the HSA wins by $846.50 instead of $1,146.50.
Federal rate 12%: FSA tax savings $838.10, FSA net value $538.10; HSA tax savings $1,084.60, HSA value $1,584.60; HSA wins by $1,046.50 At a 12% federal rate the combined rate falls to 24.65%, both sides save less tax, and the HSA still wins by $1,046.50.
FSA contribution $2,000: FSA tax savings $693.00, FSA net value $393.00; HSA tax savings $1,524.60, HSA value $2,024.60; HSA wins by $1,631.60 A smaller FSA contribution saves less tax and leaves the HSA further ahead — the FSA net value falls to $393.00.
HSA contribution $3,400: FSA tax savings $1,178.10, FSA net value $878.10; HSA tax savings $1,178.10, HSA value $1,678.10; HSA wins by $800.00 With both contributions at $3,400 the tax savings tie at $1,178.10, and the HSA wins by exactly the $500.00 seed plus the $300.00 the FSA forfeits.
FSA contribution that ties the HSA value: $6,708.79 (exact 6,708.8023) — at $6,708.79 the FSA net value is $2,024.60; one cent less, $6,708.78, the FSA net value is $2,024.59. That is above the $3,400 FSA limit for 2026, so no legal FSA contribution ties the HSA on these numbers. The star is DOLLARS (FSA contribution).
Employer seed that ties: -$646.50 — at a -$646.50 seed the HSA value is $878.10, exactly the FSA net value; one cent more, -$646.49, the HSA value is $878.11. A negative seed is impossible in practice: even a $0 seed leaves the HSA ahead by $646.50, so no real employer seed ties. The star is DOLLARS (employer seed).
Unspent amount that ties: -$846.50 — at -$846.50 unspent the FSA net value is $2,024.60, exactly the HSA value; one cent more, -$846.49, the FSA net value is $2,024.59. Unspent cannot be negative: the FSA would have to gain money from forfeiting, so no real unspent amount ties. The star is DOLLARS (unspent).
Federal rate that ties: -92.65% — at a -92.65% federal rate the combined rate is −80.00%, and both sides are -$3,020.00 — a tie; one 0.01% step up, -92.64%, and the HSA wins by $0.10. A negative tax rate is impossible: raising the rate widens the HSA lead because its contribution is larger, so no real federal rate ties. The star is a PERCENT.
The 2026 limits are the IRS figures: a health FSA limit of $3,400 (Revenue Procedure 2025-32, with a carryover of up to $680 if the plan allows it) and HSA limits of $4,400 self-only and $8,750 family (Revenue Procedure 2025-19). The model assumes you are in the 22% federal bracket, pay 5% state tax, and pay FICA on the FSA contribution — HSA contributions made through payroll also avoid FICA, which is why the same combined rate is used for both. It does not model the FSA grace period or carryover, the HSA catch-up contribution of $1,000 for savers 55 and older, the tax on HSA withdrawals for non-medical costs before 65, or the fact that an HSA needs a high-deductible health plan. With both contributions at $0 (unspent $0, seed $500) the FSA net value is $0.00 and the HSA value is $500.00 — the seed alone. With the whole $3,400 FSA contribution left unspent the FSA net value is -$2,221.90 and the HSA wins by $4,246.50. With a $3,400 FSA fully spent against a $0 HSA the FSA wins by $678.10 — the FSA can win, but only when the HSA is empty and nothing is forfeited. Rounding convention: figures are rounded to cents half-up, so rounded parts may differ by a cent from their rounded sum; the reverses are smallest-value solutions, and the exact figures ($6,708.79, -$646.50, -$846.50, -92.65%) are stated wherever the rounded figures appear.
| Output | Formula | What it means |
|---|---|---|
| Combined tax rate | federal + state + FICA | 34.65%. |
| FSA tax savings | FSA contribution × combined rate | $1,178.10. |
| FSA net value | FSA tax savings − amount left unspent | $878.10. |
| HSA tax savings | HSA contribution × combined rate | $1,524.60. |
| HSA value | HSA tax savings + employer seed | $2,024.60. |
| Difference | HSA value − FSA net value | $1,146.50. |
| Winner | larger value | HSA. |
| FSA contribution that ties the HSA value | exact 6,708.8023 (above the $3,400 limit) | $6,708.79 → $6,708.79. |
| Employer seed that ties | -$646.50 (no real seed ties) | -$646.50 → -$646.50. |
| Unspent amount that ties | -$846.50 (unspent cannot be negative) | -$846.50 → -$846.50. |
| Federal rate that ties | -92.65% (no real rate ties) | -92.65% → -92.65%. |
| HSA family $8,750 | same model | FSA tax savings $1,178.10, FSA net value $878.10; HSA tax savings $3,031.88, HSA value $3,531.88; HSA wins by $2,653.78. |
| Employer seed $0 | same model | FSA tax savings $1,178.10, FSA net value $878.10; HSA tax savings $1,524.60, HSA value $1,524.60; HSA wins by $646.50. |
| Unspent $0 | same model | FSA tax savings $1,178.10, FSA net value $1,178.10; HSA tax savings $1,524.60, HSA value $2,024.60; HSA wins by $846.50. |
| Federal rate 12% | same model | FSA tax savings $838.10, FSA net value $538.10; HSA tax savings $1,084.60, HSA value $1,584.60; HSA wins by $1,046.50. |
| FSA contribution $2,000 | same model | FSA tax savings $693.00, FSA net value $393.00; HSA tax savings $1,524.60, HSA value $2,024.60; HSA wins by $1,631.60. |
| HSA contribution $3,400 | same model | FSA tax savings $1,178.10, FSA net value $878.10; HSA tax savings $1,178.10, HSA value $1,678.10; HSA wins by $800.00. |
The math is first-principles: the tax savings are the contribution times the combined rate, the FSA net value subtracts what is left unspent, and the HSA value adds the employer seed — every figure is rounded to cents half-up, and the reverses are smallest-value solutions with the exact figures ($6,708.79, -$646.50, -$846.50, -92.65%) stated wherever the rounded figures appear. The 2026 limits are the IRS figures (FSA $3,400, Revenue Procedure 2025-32; HSA $4,400 / $8,750, Revenue Procedure 2025-19). What the model cannot do is pick YOUR plan: it does not model the FSA grace period or $680 carryover, the $1,000 HSA catch-up at 55+, the tax and penalty on non-medical HSA withdrawals before 65, or the higher deductible and out-of-pocket costs of the high-deductible plan an HSA requires. The HSA also grows tax-free and can be invested — value this model does not count. Use it to compare the tax savings, then weigh the plan costs before you choose.
Bright Side Kit. "FSA vs HSA: Which Saves You More on Taxes in 2026?" https://brightoolbox.com/fsa-vs-hsa/ Accessed October 26, 2026.On the defaults, the HSA — by $1,146.50. The HSA saves $1,524.60 of tax and adds a $500.00 employer seed for a value of $2,024.60, while the FSA saves $1,178.10 of tax and loses $300.00 unspent for a net value of $878.10.
FSA $3,400; HSA $4,400 self-only and $8,750 family. The FSA limit is in Revenue Procedure 2025-32 (carryover up to $680 if the plan allows it); the HSA limits are in Revenue Procedure 2025-19.
$6,708.79. That is above the $3,400 FSA limit for 2026, so no legal FSA contribution ties the HSA on these numbers. The exact figure is $6,708.8023.
The HSA still wins by $646.50. Without the $500.00 seed the HSA value is $1,524.60 against the FSA net value of $878.10. The seed is $500.00 of the $1,146.50 gap.
Yes — when the HSA is empty and nothing is forfeited. With a $3,400 FSA fully spent against a $0 HSA the FSA wins by $678.10. But leaving the whole $3,400 unspent makes the FSA net value -$2,221.90.
The FSA grace period and carryover, the $1,000 HSA catch-up at 55+, tax and penalties on non-medical HSA withdrawals before 65, and the higher deductible of the high-deductible plan an HSA needs. It also does not count the HSA’s tax-free growth when invested.
It changes the size of the gap, not the winner here. At a 12% federal rate the combined rate is 24.65% and the HSA wins by $1,046.50 instead of $1,146.50. The HSA’s larger contribution means a higher rate always widens its lead.
Tax savings = contribution × (federal + state + FICA). On the defaults: FSA $3,400.00 × 34.65% = $1,178.10, minus $300.00 unspent = $878.10; HSA $4,400.00 × 34.65% = $1,524.60, plus a $500.00 seed = $2,024.60.