What This Calculator Does
The Microapp HSA Contribution Calculator computes your 2025 max contribution, the immediate tax savings from contributing the max, and a 30-year projection if you invest rather than spend the HSA balance. The HSA is the most tax-advantaged account in the US tax code — and most users dramatically underuse it.
• 2025 max contribution: $8,550
• Federal tax savings: $1,881
• State tax savings: $428
• FICA savings (payroll): $654
• Total annual tax savings: $2,963 — meaning the $8,550 contribution effectively costs you only $5,587 of take-home pay
• Invested at 7% return for 30 years: ~$870,000 on $256,500 of contributions
Even better: this $870k can come out tax-free for medical expenses (and most retirees have plenty).
The Triple Tax Advantage Explained
No other US tax-advantaged account combines all three benefits the HSA offers:
| Benefit | HSA | Roth IRA | Traditional 401(k) |
|---|---|---|---|
| Tax-deductible contributions | Yes | No | Yes |
| Tax-free growth | Yes | Yes | Tax-deferred |
| Tax-free qualified withdrawals | Yes (medical, any age) | Yes (any purpose, 59½+) | No (taxed as income) |
The HSA is the only account where you get a tax deduction now AND tax-free growth AND tax-free qualified withdrawals. Add FICA savings if contributed through payroll (an additional 7.65%) and the math is overwhelming.
The "Stealth Retirement Account" Strategy
Most HSA users treat the HSA like a checking account for medical bills — money in, money out. This is the wrong play. The optimal strategy:
- Max your HSA contribution every year ($4,300 single / $8,550 family for 2025).
- Invest the HSA balance in low-cost index funds (most HSA providers offer Vanguard or similar index funds).
- Pay current medical bills out of pocket from your regular budget — NOT from the HSA.
- Save every medical receipt forever (digitize them — there's no time limit on HSA reimbursements).
- Reimburse yourself in retirement — by then, you'll have decades of accumulated medical receipts AND a large invested HSA balance.
Why this works: every $1 you keep in the HSA grows tax-free for decades. The IRS has confirmed there's no time limit on HSA reimbursements — you can pay for a doctor visit today and reimburse yourself 30 years from now, completely tax-free, as long as you have the receipt and didn't already deduct it elsewhere.
The Numbers Behind "Stealth Retirement"
Maxing HSA contributions for 30 years at 7% return:
| Coverage type | Annual contribution | 30-year invested projection |
|---|---|---|
| Single | $4,300 | ~$437,000 |
| Family | $8,550 | ~$870,000 |
| Family + 55+ catch-up (last 10 years) | $8,550 → $9,550 | ~$890,000 |
For a married couple where both spouses are eligible for individual HSAs (each works at a company offering an HDHP), the math compounds further — though family coverage usually means one shared HSA account.
HSA vs FSA — Don't Confuse Them
FSA (Flexible Spending Account) and HSA are often confused but work very differently:
- HSA: Yours forever. Funds carry over year to year. Investable. Portable across jobs.
- FSA: Use it or lose it (with limited carryover). Not investable. Forfeited if you change jobs mid-year.
HSA wins on every dimension except one: FSA doesn't require an HDHP. If you don't have access to an HDHP, FSA is the only tax-advantaged medical account available — but it's much less powerful.
Where to Open an HSA
If your employer offers an HSA, use it for payroll deduction (captures the 7.65% FICA savings, which direct deposits don't). Many employer HSAs have high admin fees and limited investment options though. The standard pro move: contribute via payroll to capture FICA, then periodically transfer balances to a better HSA provider:
- Fidelity HSA: Zero account fees. Full brokerage investment options. Available to anyone.
- Lively HSA: Zero account fees. Schwab brokerage integration for investments. Modern UX.
- HSA Bank: Common employer-provided option. Higher fees but adequate.
The IRS allows free trustee-to-trustee transfers between HSAs once per year. Set up Fidelity or Lively as your "real" HSA, then sweep employer contributions over quarterly or annually.
What Counts as a Qualified Medical Expense?
The IRS list is broad — most healthcare-related expenses qualify:
- Doctor visits, surgeries, hospital stays, ambulance rides
- Prescription drugs (US and international, with exceptions)
- Dental: cleanings, fillings, crowns, orthodontics (kids and adults)
- Vision: exams, glasses, contacts, LASIK
- Hearing: exams, hearing aids
- Mental health: therapy, psychiatric treatment
- Long-term care insurance premiums
- Medicare premiums (Parts B, D, and Medigap) at age 65+
- Substance abuse treatment
- Many over-the-counter medications (since 2020)
- Menstrual products (since 2020)
What does NOT qualify: cosmetic procedures (unless medically necessary), gym memberships (unless prescribed for a specific medical condition), supplements (with rare exceptions), insurance premiums in general (except long-term care and Medicare).
State-Level Quirks
Most states follow federal HSA tax treatment. Two important exceptions:
California: Taxes HSA contributions and earnings at the state level. You still get the federal tax benefits, but California treats the HSA as a regular taxable account for state purposes. This eliminates the state tax savings shown in this calculator if you're in CA — set state tax to 0% in the input.
New Jersey: Same as California — taxes HSA contributions and earnings at the state level.
All other states either follow federal treatment (give the deduction) or have no state income tax (TX, FL, NV, WA, AK, SD, WY, TN, NH).
Common Mistakes
Treating the HSA like a checking account. Spending current medical bills from the HSA prevents the balance from growing. If you can afford to pay out of pocket from other funds, do — and let the HSA invest.
Not investing the balance. Many HSA providers default to a low-yield "cash" option. You have to actively choose investment funds. Check your provider's interface — there's usually a "manage investments" or "transfer to investment account" option.
Not capturing the FICA savings. Contributing directly to the HSA outside payroll loses the 7.65% FICA savings (plus your employer's 7.65% match). Always contribute via payroll deduction if available.
Letting receipts sit unsorted. The "save receipts and reimburse later" strategy only works if you can actually find the receipts later. Use a digital receipt-tracking app (FYISave, HSA Receipt Tracker) or even just a Google Drive folder.
Stopping HSA contributions when you change jobs. The HSA is yours, not your employer's. You keep it forever. Continue contributing (directly if your new employer doesn't offer payroll deduction).
Educational Tool — Not Tax or Medical Advice
This calculator implements the standard HSA contribution math using 2025 IRS limits. It assumes you're eligible (HDHP-enrolled), uses approximate marginal rates, and projects investment growth at a constant return. For specific tax decisions, consult a CPA. For HSA eligibility questions, consult your benefits administrator or an insurance broker.
Related Tools
Use the 401(k) Calculator to project your other major retirement account. The Roth IRA Calculator rounds out the trio of tax-advantaged retirement accounts. For projecting growth on any investment account at custom contribution + return assumptions, the Compound Interest Calculator is the general-purpose tool.