HSA & FSA Paycheck Impact Calculator
See how pre-tax HSA and FSA contributions cut your take-home pay, what each dollar really costs after tax, and the FICA break a 401(k) never gets.
HSA & FSA Paycheck Impact Calculator
Your contributions
Enter your salary, state, and pre-tax amounts. HSA and FSA payroll deductions are modeled as Section 125 pre-tax, so they cut income tax and FICA.
Enter your annual salary.
2026 marginal-rate estimate. It uses the federal bracket rate on your top dollars of income, the FICA rate that applies to your salary, and a single flat state marginal rate (graduated states use the top marginal rate, which overstates the state line at lower incomes). It does not re-run your full return or model the standard deduction. HSA and FSA payroll deductions are treated as pre-tax for income tax and FICA; California and New Jersey tax HSA contributions at the state level. Not filing-grade: it excludes local taxes, itemized deductions, and credits.
How HSA and FSA contributions change your paycheck
When you route money into an HSA or a health FSA through payroll, it leaves your gross pay before taxes are calculated. That means your taxable wages shrink, so your paycheck drops by less than the amount you set aside. The gap between what you contribute and what your check loses is tax you no longer pay, and it is the whole point of a pre-tax account.
The useful number is the net cost per dollar. Take a worker contributing $3,400 to a health FSA at a 22 percent federal marginal rate, 7.65 percent FICA, and a 5 percent state rate. Their combined savings rate is about 34.65 percent, so the $3,400 saves roughly $1,178 in tax. Take-home falls by only about $2,222 over the year, which means each pre-tax dollar really costs about 65 cents. Spread across 26 biweekly checks, that is a drop of roughly $85 per paycheck for $130 of contribution.
The FICA edge: why an HSA beats a 401(k) dollar-for-dollar
A traditional 401(k) deferral lowers your federal and state income tax, but you still pay the full 7.65 percent employee FICA (6.2 percent Social Security plus 1.45 percent Medicare) on that money. HSA and health FSA payroll contributions run through a Section 125 cafeteria plan, so they escape FICA too. On the same $1 contributed, an HSA saves that extra 7.65 percent up front that a 401(k) does not.
Put a $3,000 HSA contribution next to a $3,000 traditional 401(k) contribution at the same income. The income tax break is identical, but the HSA also skips about $230 of FICA that the 401(k) still pays. To see the 401(k) side in the same format, use the 401(k) paycheck impact calculator. If you are weighing a raise or bonus against these deductions, the bonus tax take-home calculator and the net to gross salary calculator cover the other side of the paycheck.
State tax on HSAs: the California and New Jersey exception
In 48 states and DC, an HSA contribution is exempt from state income tax exactly as it is exempt federally. California and New Jersey are the two states that do not conform. In those two states, HSA contributions are added back to your state wages (W-2 Box 16), so the HSA still saves federal income tax and FICA but not state income tax. This calculator drops the HSA out of the state line automatically when you pick California or New Jersey.
Health FSAs are not affected by this. FSA contributions stay pre-tax for state income tax in every state, including California and New Jersey. If you live in one of those two states and want the full state break, the FSA portion of your contribution still delivers it.
2026 contribution limits and how much room you have left
For 2026, the HSA limit is $4,400 for self-only coverage and $8,750 for family coverage, and anyone age 55 or older can add a $1,000 catch-up. The health FSA limit is $3,400, with a carryover of up to $680 into the next plan year. The calculator caps your entry at these limits, floors your remaining room at zero, and shows how much of each account you have left to fund before year end.
This web version is a quick marginal-rate estimate, fine for planning. When you need exact per-state withholding, both accounts modeled inside your real paycheck, and saved profiles to compare pay frequencies, download the Stub44 Salary Calculator app. Planning around a partner's income too? The two-income household take-home calculator puts both paychecks in one view.
Frequently Asked Questions
Common questions about hsa & fsa paycheck impact calculator
How much does an HSA or FSA actually reduce my take-home pay?
By less than the amount you contribute, because the money comes out of your paycheck before federal income tax, Social Security, Medicare, and (in most states) state income tax. If your combined marginal rate is around 32 percent, a $1 contribution drops your check by about 68 cents. The rest is tax you no longer pay. Enter your salary, state, and contribution above to see the exact per-paycheck drop.
Do HSA and FSA contributions lower my Social Security and Medicare (FICA) taxes?
Yes. Both HSA and health FSA payroll deductions run through a Section 125 cafeteria plan, so they escape the 6.2 percent Social Security and 1.45 percent Medicare employee tax as well as federal income tax. That 7.65 percent FICA break is the part most people miss, and it is money a traditional 401(k) contribution still pays.
Why does an HSA save more on taxes than a 401(k)?
A traditional 401(k) deferral escapes federal and state income tax but still pays the full 7.65 percent FICA. An HSA payroll contribution escapes income tax and FICA. On the same dollar, the HSA saves an extra 7.65 percent up front. Our 401(k) paycheck impact calculator shows the 401(k) side for comparison.
What are the 2026 HSA and FSA contribution limits?
For 2026 the HSA limit is $4,400 for self-only coverage and $8,750 for family coverage, plus a $1,000 catch-up if you are age 55 or older. The health FSA limit is $3,400, with a carryover of up to $680 into the next plan year. The calculator caps your entry at these limits and shows the room you have left.
Are HSA contributions taxed by my state?
In 48 states and DC, no: HSA contributions are exempt from state income tax the same way they are exempt federally. California and New Jersey are the two exceptions. They tax HSA contributions at the state level, so in those states your HSA saves federal income tax and FICA but not state income tax. FSA contributions are pre-tax for state purposes everywhere, including California and New Jersey.
HSA vs. FSA: which one saves more on taxes per paycheck?
Per dollar, both save the same in most states, since both come out before income tax and FICA. Where they split is the fine print. The HSA family limit is much higher. An HSA needs a high-deductible health plan and the money rolls over, while most FSA funds are use-it-or-lose-it. And California and New Jersey tax HSA contributions but leave FSA ones alone. Enter both above to see the combined effect.
How much does each pre-tax dollar really cost me after the tax break?
It equals one minus your combined marginal savings rate. Add your federal marginal rate, the FICA rate that applies to you, and your state marginal rate; that sum is what you save per dollar, and the rest is the real cost. At a 22 percent federal rate, 7.65 percent FICA, and a 5 percent state rate, you save about 34.65 percent, so each dollar costs roughly 65 cents. The calculator computes this from your inputs.
Does contributing to an HSA or FSA lower my future Social Security benefit?
It can slightly. Because HSA and FSA payroll contributions reduce the wages subject to Social Security tax, they also reduce the wages counted toward your benefit calculation. The effect is small for most workers, and it is zero if your salary is already above the 2026 Social Security wage base of $184,500, since those top dollars are not taxed for Social Security either way.