Compare tax savings, employer match, and investment growth side by side to see whether a Health Savings Account (HSA) or a Flexible Spending Account (FSA) saves you more money — this year and over time.
Three real-world scenarios, computed with the exact same formulas as the calculator above.
Scenario: Single filer in the 22% federal bracket contributes the maximum $4,300 to an HSA and $3,200 to an FSA, expects $1,500 of medical expenses this year, plans to tap the HSA money in 5 years, and invests it at a 7% annual return.
Scenario: Married couple in the 24% bracket with a family HDHP contributes the family maximum $8,550 to one HSA vs $6,400 across two health FSAs, expects $5,000 of medical expenses, and does not invest the HSA balance.
Scenario: A low spender whose employer does not offer an HDHP (so an HSA is off the table) contributes $3,200 to a health FSA, is in the 24% federal bracket, and only spends $800 of the balance. An FSA is still worth using — but forfeiture bites.
The calculator models one year of contributions for each account, adds the tax savings both accounts deliver, layers in tax-free investment growth for the HSA, subtracts any use-it-or-lose-it FSA forfeiture, and crowns a winner. Here is each step.
Contributions made through payroll avoid federal income tax, state income tax, and the 7.65% FICA payroll tax (Social Security + Medicare). Both HSA and FSA contributions get this treatment.
Each dollar contributed avoids tax at your combined rate, so the tax savings is simply the contribution times the combined rate.
Unlike an FSA, an HSA can be invested in mutual funds, ETFs, and other assets. Growth inside an HSA is completely tax-free — no capital gains, no dividends tax, no tax on withdrawal for medical expenses.
FSA money that you do not spend by year-end is forfeited, except that your employer may allow up to $640 to carry over into the next plan year. Any amount above your medical spending and the carryover is lost.
The HSA total adds your contribution, employer match, tax savings, and investment growth. The FSA total adds your contribution, employer match, and tax savings, then subtracts the forfeited amount. The higher total wins the "Best Choice" badge.
⚠️ Important: An HSA requires enrollment in a High-Deductible Health Plan (HDHP). If you do not have an HDHP you cannot contribute to an HSA — an FSA (or limited-purpose FSA) is then the option. An HSA also cannot be combined with a general-purpose health FSA in the same year.
Both accounts let you pay for qualified medical expenses with pre-tax dollars, but they are built for very different situations. An HSA (Health Savings Account) is the only account in the U.S. with a triple tax advantage — but it comes with a catch: you must be enrolled in a High-Deductible Health Plan (HDHP). An FSA (Flexible Spending Account) works with any health plan but punishes you for over-saving with its use-it-or-lose-it rule.
| Feature | HSA | FSA |
|---|---|---|
| Eligible health plan | HDHP required | Any plan type |
| 2026 contribution limit | $4,300 self / $8,550 family (+$1,000 catch-up 55+) | $3,200 |
| Money rolls over | Yes — forever, no expiration | Limited — up to $640 carryover, rest is use-it-or-lose-it |
| Can invest | Yes — funds, ETFs, stocks, tax-free growth | No |
| Tax advantages | Triple: pre-tax in, tax-free growth, tax-free withdrawals for medical | Double: pre-tax in, tax-free withdrawals |
| Ownership | Yours — portable between employers | Employer-sponsored — generally lost when you leave the job |
| After age 65 | Works like a retirement account; non-medical withdrawals taxed like an IRA | N/A |
The single biggest difference is what happens to money you do not spend. Every unspent HSA dollar is yours forever and can be invested to grow tax-free for decades. Every unspent FSA dollar above the $640 carryover disappears at year-end. That is why the HSA is almost always the better long-term vehicle — and why this calculator exists: to show you exactly how much better, with your numbers.
The HSA is the only account in the U.S. tax code that delivers all three of these benefits at once — which is why financial planners call it the most powerful savings vehicle available:
Every dollar you contribute is subtracted from your taxable income before federal, state, and 7.65% FICA payroll taxes are calculated. A $4,300 contribution in the 22% bracket saves about $1,274.95 in taxes the year you make it.
Interest, dividends, and capital gains inside an HSA grow completely tax-free. Over 20 years at 7%, a $4,300 balance grows by roughly $12,340 — and you never pay a penny of tax on that growth.
Withdrawals for qualified medical expenses (doctor visits, prescriptions, dental, vision, and more — see IRS Publication 502) are tax-free at any age, at any time, with no receipt deadline.
For comparison, an FSA gives you the first benefit (pre-tax contributions) and the third (tax-free withdrawals) but skips the middle one — there is no investment component at all. The missing growth leg is often worth tens of thousands of dollars over a career.
There is no universal winner — the right account depends on your health plan, your medical spending, and your time horizon. Use these decision rules as a starting point, then run your own numbers in the calculator:
You are enrolled in a high-deductible health plan and can comfortably cover the deductible from savings. This is the only way to get an HSA.
You do not expect to spend the balance soon. Invested HSA dollars grow tax-free for years or decades, turning medical savings into a retirement asset.
After 65 the HSA behaves like a retirement account, and you can reimburse past medical expenses from any year — a powerful tax-planning tool.
Without a high-deductible plan you cannot contribute to an HSA at all. A health FSA (or limited-purpose FSA paired with an HSA) is the standard alternative.
You know exactly what you will spend on copays, prescriptions, and care this year. If you can spend the full balance, the FSA's pre-tax savings are nearly as good as an HSA's.
You prefer guaranteed, immediate tax savings over long-term investment growth and do not want to manage an investment account.
⚠️ HDHP Requirement: An HSA requires enrollment in a High-Deductible Health Plan (HDHP). If you do not have an HDHP you cannot contribute to an HSA — an FSA (or FSA limited-purpose) is then the option. Also note: an employer match makes either account dramatically better — if your employer contributes to your HSA or FSA, always contribute at least enough to capture the full match.
Generally, no — if you have an HSA, you cannot also have a general-purpose health FSA that reimburses regular medical expenses before your deductible is met. However, you can pair an HSA with a limited-purpose FSA, which only covers dental and vision expenses. Many employers offer this exact combination to get the best of both worlds.
For 2026, the HSA contribution limit is $4,300 for self-only coverage and $8,550 for family coverage, plus a $1,000 catch-up contribution for account owners aged 55 and older. The health FSA limit for 2026 is $3,200. Limits are adjusted for inflation each year by the IRS, so always confirm the current figures before contributing.
Yes. To be HSA-eligible you must be enrolled in a qualifying High-Deductible Health Plan (HDHP) and have no disqualifying coverage. For 2026, an HDHP is generally a plan with a deductible of at least $1,700 for self-only coverage ($3,400 for family) and out-of-pocket maximums capped around $8,550 for self-only ($17,100 for family). If you do not have an HDHP, you cannot contribute to an HSA — an FSA or limited-purpose FSA is then your pre-tax option.
It depends on your employer's plan design. Under the use-it-or-lose-it rule, unused funds are forfeited — but many plans now allow one of two relief options: a carryover of up to $640 into the next plan year, or a grace period of up to 2.5 months to spend the previous year's balance. Some plans offer both (with a reduced carryover) and a few offer neither. Check your plan document — and if your plan offers no relief, be conservative with your election.
Yes — most HSA custodians let you invest your balance in mutual funds, ETFs, and sometimes individual stocks once the account exceeds a cash threshold (often $1,000–$2,000, which must stay in cash). Investment earnings grow completely tax-free, and withdrawals for qualified medical expenses are tax-free too. A common strategy is to pay current medical bills out of pocket, let the HSA grow invested for years, and reimburse yourself later — maximizing the tax-free compounding this calculator models.
At 65 your HSA essentially becomes a retirement account. Withdrawals for qualified medical expenses remain tax-free forever, and withdrawals for any other purpose are taxed as ordinary income — but the 20% early-withdrawal penalty disappears at 65. After you enroll in Medicare you can no longer make new HSA contributions, but you can keep the account, keep investing, and keep withdrawing tax-free for medical costs. Many retirees use their HSA to pay Medicare premiums and long-term care expenses.
⚠️ Disclaimer: Contribution limits and tax rules change annually and depend on your specific plan and filing status. This calculator provides estimates, not tax advice. Consult a tax professional before making decisions.