HSA vs FSA Calculator
Compare U.S. HSA vs FSA tax savings + long-term growth. Picks the right account from your medical spend, HDHP eligibility + investment horizon. Free.
HSA vs FSA Calculator
⚠ Disclaimer: Estimates only. Not investment advice. RECATOOLS is not a licensed or registered investment adviser in any jurisdiction. Past performance does not guarantee future results. Trading and investing carry risk of partial or total loss of capital.
Compares one year of a Health Savings Account (HSA — needs HSA-eligible coverage, the balance is yours to keep and invest) with one year of a health Flexible Spending Account (FSA — no HDHP needed, but unused money is forfeited at year end beyond any carryover). Then shows where the HSA alone can go if you invest it. You can fund one or the other, not both: a general-purpose health FSA ends HSA eligibility.
Payroll-tax rates: Social Security 6.2% up to the USD 184,500 wage base for 2026, Medicare 1.45% on all wages, plus 0.9% Additional Medicare Tax over USD 200,000 (IRS Publication 15). The projection repeats this year's HSA contribution every year, adds it at each year end and assumes a steady return; fees are not modelled.
How to Use the HSA vs FSA Calculator
Confirm HSA eligibility
An HSA needs a High Deductible Health Plan (HDHP) — for 2026, minimum deductible USD 1,700 single / USD 3,400 family, with out-of-pocket maximum at most USD 8,500 / USD 17,000 (Rev. Proc. 2025-19). From January 2026 a bronze or catastrophic plan available as individual coverage through an ACA Exchange also counts, and a direct primary care arrangement no longer disqualifies you (IRS Notice 2026-5). Otherwise, the FSA is your option.
Estimate annual medical spend honestly
Prescriptions, deductibles, copays, dental, vision, OTC. For FSA, contribute close to (but not above) this number to avoid forfeiture. For HSA, there is no forfeiture — an unused balance stays yours and can be invested.
Set your tax position
Enter your federal and state marginal rates separately, because California and New Jersey do not follow the federal HSA exclusion. Then the payroll part: an FSA, and an HSA paid through a §125 cafeteria plan, also skip Social Security and Medicare tax — 7.65% under the wage base, 1.45% above it — which a 401(k) deferral does not. An HSA you pay into directly saves income tax only.
Use a realistic investment horizon
HSA's killer feature: invest the balance for decades. The "pay-medical-out-of-pocket, invest-HSA, reimburse-later" strategy compounds the triple tax advantage. Pick a horizon matching when you'll actually use the funds — for many young workers this is age 65.
HSA — The Most Tax-Advantaged Account in US Personal Finance
The Triple Tax Advantage
Health Savings Accounts (HSAs) are the only US account with three layers of tax benefit: (1) contributions are pre-tax (and, through payroll, also exempt from FICA, unlike an IRA), (2) growth is tax-free, (3) qualified withdrawals are tax-free. Compare to Traditional IRA (pre-tax in, tax-deferred growth, taxable withdrawal — single tax benefit) or Roth IRA (post-tax in, tax-free growth + withdrawal — double tax benefit). Because both the contribution and the qualified withdrawal escape federal income tax, and payroll contributions also escape FICA, a dollar in an HSA beats the same dollar in either IRA for medical spending — less so in California and New Jersey, which tax HSA contributions. For workers who qualify (an HDHP is required), funding the HSA early is often the highest-leverage move available.
The unique 2026 limits: USD 4,400 self-only / USD 8,750 family + USD 1,000 catch-up at age 55+. A married couple with family coverage, both 55+: USD 10,750/year, the second USD 1,000 going into the other spouse's own HSA. Over 10 years that's USD 107,500 of contributions, growing tax-free, withdrawable tax-free for any qualified medical expense across the lifetime — including Medicare premiums in retirement. After age 65, HSA withdrawals for ANY purpose are penalty-free (taxable as ordinary income for non-medical) — making it function essentially as a "Super-Roth IRA" for healthcare.
The "Save Receipts" Strategy
The single most powerful HSA tactic: pay current medical bills out-of-pocket (from your checking account), save the receipts, and let the HSA compound untouched for decades. The IRS sets no time limit on HSA reimbursement (IRS Notice 2004-50, Q&A-39) — you can reimburse yourself in 2055 for a USD 200 doctor visit paid in 2026, fully tax-free, provided the expense was incurred after the HSA was opened. Meanwhile the HSA balance grows tax-free. The strategy converts the HSA from a "current-medical-cost account" into a retirement account whose tax treatment is at least as favourable as a Roth IRA's.
Requirements: keep copies of every medical receipt and a running record of which expenses remain unreimbursed — Notice 2004-50 requires records sufficient to show each distribution paid a qualified expense that was not reimbursed elsewhere — and hold the HSA at a custodian that allows investment beyond cash rather than leaving the balance in a low-yield deposit.
"The receipt strategy in numbers: contribute USD 4,400 at the start of each year for 30 years and earn 7% a year, and the balance compounds to roughly USD 444,000 — about USD 312,000 of it growth that was never taxed. Every dollar can come out tax-free against saved receipts for expenses you paid from your own pocket along the way."
When FSA Makes Sense
Not everyone qualifies for HSA. If you have a low-deductible PPO or HMO (not an HDHP), or your spouse's family-coverage HDHP doesn't include you, you can't contribute to an HSA. FSA is the fallback. The trade-offs: lower contribution cap (USD 3,400 for 2026), use-it-or-lose-it (a plan may offer a carryover of up to USD 680 or a grace period of up to 2½ months, never both, or neither — and there is no investment growth). The FSA strategy is "estimate carefully, don't over-fund". For families with predictable spending — orthodontia, glasses, regular prescriptions — FSA can be a significant tax win. For families with low spend, the FSA tax savings may not justify the year-end-deadline stress.
The Most Common HSA Mistakes
Three high-frequency mistakes that erase the HSA's tax-advantage edge: (1) Leaving the balance in cash: the gap between a deposit yield and a diversified portfolio return, compounded over decades, is the largest single cost most account holders incur — use a custodian that lets you invest. (2) Using the HSA as a checking account for current medical bills instead of letting it compound — pay out of pocket and save receipts for decade-later reimbursement. (3) Not planning who inherits it. Only a spouse named as beneficiary inherits the account as their own HSA; for anyone else, including your estate, it stops being an HSA and its fair market value becomes taxable in the year you die (IRS Publication 969). Name your beneficiaries deliberately.
One account is taxed three times in your favour; the other you forfeit
HSA = triple tax advantage: pre-tax in, tax-free growth, tax-free out for medical. Only account with all three.
2026 HSA cap: USD 4,400 single / USD 8,750 family + USD 1,000 catch-up at 55+.
2026 FSA cap: USD 3,400. A plan may allow a USD 680 carryover or a 2½-month grace period — not both.
HSA requires enrollment in HDHP: minimum deductible USD 1,700 (single) / USD 3,400 (family).
Paid through payroll, HSA and FSA money also escapes FICA — 7.65% under the wage base; a 401(k) deferral does not.
HSA no time limit on reimbursement — pay medical now, reimburse decades later, fully tax-free.
After age 65, HSA withdrawals for non-medical are penalty-free (taxable as ordinary income).
HSA balance is yours forever — no use-it-or-lose-it, portable between jobs and into retirement.
FSA is use-it-or-lose-it; some plans allow a carryover (max USD 680 for 2026) or a grace period of up to 2½ months.
Employer HSA contributions count toward the same annual limit as your own (IRC §223(b)(4)); they are excluded from your income and are yours from day one.
Frequently Asked Questions
- Generally no for regular FSA — it disqualifies you from HSA contributions. EXCEPTION: a limited-purpose FSA is HSA-compatible because it pays only for items such as dental and vision care, plus preventive care (IRS Publication 969). If your employer offers it, it can sit alongside the HSA — dental and vision through the limited FSA, everything else through the HSA. Best combo for families with significant dental/vision spend.
- HSA: the balance is yours, period. You can move it to any HSA custodian by trustee-to-trustee transfer, or roll it over yourself once in any 12-month period (IRC §223(f)(5)). A health FSA balance is generally forfeited when employment ends unless you elect COBRA continuation for the FSA. Once you have left, compare custodians on fees and investment access before deciding where the balance lives.
- Yes — nothing in IRC §223 restricts an HSA to cash, and many custodians open a brokerage or fund menu once the balance clears a custodian-set minimum. Check that minimum and the fee schedule before choosing a custodian; over a multi-decade horizon, forgone growth in a cash-only account is usually the larger cost.
- Without HSA-eligible coverage you can't contribute to an HSA. From 2026 check whether your plan is a bronze or catastrophic plan available through an ACA Exchange — those now count (IRC §223(c)(2)(H)). Otherwise your tax-advantaged option is an FSA, if your employer offers one. FSA still saves you income + FICA tax on the amount contributed — significant savings if you contribute close to your actual medical spend. Plan carefully: estimate annual spend accurately, since unused balance forfeits at year-end (with limited carryover).
- Run the math, don't auto-switch. HDHP premium is lower but deductible is higher. Compare: (lower HDHP premium × 12) + (HSA tax savings) + (expected out-of-pocket up to deductible) vs (PPO premium × 12) + (PPO out-of-pocket). For adults with predictable low medical spend the HDHP + HSA combination usually wins; for families expecting to reach the deductible every year, the PPO may cost less overall.
- IRS Publication 502 lists qualified medical expenses. Major categories: deductibles, copays, prescriptions, dental, vision, OTC medications (post-CARES Act 2020), menstrual products, mental health, fertility, chiropractic, acupuncture. NOT covered: cosmetic procedures, vitamins/supplements without prescription, gym memberships (unless prescribed). HSA-specific: although an HSA cannot generally pay insurance premiums, COBRA continuation premiums, qualified long-term-care premiums, premiums while on unemployment compensation and, from 65, Medicare premiums other than Medigap are allowed (IRC §223(d)(2)(C)).
- From the first month you are enrolled in Medicare your HSA contribution limit is zero. The balance is untouched and keeps growing tax-free; withdrawals stay tax-free for qualified medical expenses, which from 65 include Medicare premiums other than Medigap (IRC §223(d)(2)(C)). The trap is backdated enrolment: if you apply for Medicare late and the coverage is made retroactive, contributions made during the retroactive months become excess contributions (IRS Publication 969).
- Yes — many employers seed the account to encourage HDHP enrolment. Employer contributions count against the IRS limit (your personal contribution + employer = the cap). They're vested immediately (unlike 401(k) match) and follow you when you leave. Don't double-fund — coordinate to stay at-or-below the IRS limit.
- No — Dependent Care FSA (DCFSA) is separate from health FSA. DCFSA cap USD 7,500 a year from 2026 (USD 3,750 if married filing separately), raised from USD 5,000 by Pub. L. 119-21 (IRC §129(a)(2)(A)). Covers daycare, after-school care, summer camps for kids under 13 (or any age for disabled dependents) so you can work. Also use-it-or-lose-it. DCFSA is the most underutilized tax savings for working parents — it saves the marginal tax + FICA on up to USD 7,500 of childcare spending.
- The eligibility test in IRC §223(c)(1) is about coverage — an HDHP, no other disqualifying coverage, no Medicare, not claimed as someone else's dependent — not citizenship or visa type. Whether the federal tax benefit is worth anything to you depends on your US tax position, so check that first. If you later leave the US the balance remains yours, and receipts for qualified expenses incurred after the HSA was opened can be reimbursed later.
Method & sources
How it computes
HsaKernel, integer cents. Each account's annual saving = contribution (capped at that year's IRS limit, +$1,000 HSA catch-up at 55) × (federal rate + state rate unless CA/NJ exclude it + payroll tax if a §125 salary reduction: 7.65%, 1.45% over the wage base, 2.35% over $200k). FSA net = saving − amount forfeited after any carryover. HSA growth: the contribution repeated yearly, added at year end, compounded at the entered return.
What this tool implements
- HSA limits and HDHP thresholds by year: 2025 $4,300 / $8,550, deductible ≥ $1,650 / $3,300, out-of-pocket ≤ $8,300 / $16,600 (Rev. Proc. 2024-25); 2026 $4,400 / $8,750, ≥ $1,700 / $3,400, ≤ $8,500 / $17,000 (Rev. Proc. 2025-19); $1,000 catch-up at 55+ (IRC §223(b)(3), not indexed)
- Health FSA salary-reduction limit and maximum carryover: 2025 $3,300 / $660 (Rev. Proc. 2024-40 §3.16); 2026 $3,400 / $680 (Rev. Proc. 2025-32 §3.15). A plan may offer a carryover or a grace period of up to 2½ months, not both (Publication 969 (2025)); grace-period money is counted as lost because only expenses in those months rescue it
- Payroll tax is saved only on salary reductions through a §125 cafeteria plan (Publication 15 (2026): such HSA contributions "aren't wages"); employee rates 6.2% Social Security to the $184,500 wage base, 1.45% Medicare, 0.9% Additional Medicare Tax over $200,000. A health FSA is always a salary reduction; an HSA paid directly saves income tax only
- State: California does not recognise HSAs (FTB Publication 1001); New Jersey's 2025 NJ-1040 instructions exclude Archer MSAs but not HSAs, and cafeteria-plan benefits "but not salary reduction" plans — so no state saving is counted on the HSA in either state, or on the FSA in New Jersey
- Pub. L. 119-21 HSA changes from 2026 — bronze and catastrophic Exchange plans treated as HDHPs, direct primary care arrangements no longer disqualifying, telehealth safe harbour permanent — per IRS Notice 2026-5 and IRC §223(c)
- The verdict compares one year of each account; the HSA's invested balance is reported separately. The two are alternatives: a general-purpose health FSA is disqualifying coverage, a limited-purpose FSA is not (Publication 969)
Sources
- Internal Revenue Service. Rev. Proc. 2024-25 — 2025 inflation-adjusted amounts for Health Savings Accounts. https://www.irs.gov/pub/irs-drop/rp-24-25.pdf
- Internal Revenue Service. Rev. Proc. 2025-19 — 2026 inflation-adjusted amounts for Health Savings Accounts and high-deductible health plans. https://www.irs.gov/pub/irs-drop/rp-25-19.pdf
- Internal Revenue Service. Rev. Proc. 2024-40 §3.16 — 2025 health FSA salary-reduction limit and carryover. https://www.irs.gov/pub/irs-drop/rp-24-40.pdf
- Internal Revenue Service. Rev. Proc. 2025-32 §3.15 — 2026 health FSA salary-reduction limit and carryover. https://www.irs.gov/pub/irs-drop/rp-25-32.pdf
- 26 U.S.C. §223 — Health savings accounts: catch-up contribution, Medicare cut-off, employer contributions, 20% additional tax and the age-65 exception. https://www.law.cornell.edu/uscode/text/26/223
- Internal Revenue Service. Notice 2004-50, Q&A-39 — no time limit on HSA reimbursement of qualified expenses incurred after the HSA was established. Internal Revenue Bulletin 2004-33. https://www.irs.gov/irb/2004-33_IRB
- Internal Revenue Service. Publication 969 (2025), Health Savings Accounts and Other Tax-Favored Health Plans. https://www.irs.gov/pub/irs-pdf/p969.pdf
- Internal Revenue Service. Publication 15 (2026), (Circular E), Employer's Tax Guide — Social Security and Medicare rates, the $184,500 wage base, Additional Medicare Tax, HSA contributions under a §125 plan. https://www.irs.gov/pub/irs-pdf/p15.pdf
What can make this go out of date
- IRS re-indexes the HSA and HDHP amounts each spring (Rev. Proc. 2026-24 already sets 2027) and the health FSA limit each autumn; the 2027 FSA figure was not published on 2026-10-16, so the page offers 2025 and 2026 until it is.
- State conformity is a legislative choice and can change; California and New Jersey are the two states modelled as not following the federal HSA exclusion.
Abridged — the full review record for this tool runs longer than the list above.
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