Every article says an HSA is "triple tax-advantaged" and stops there. This calculator prices the advantage: the deduction you get going in, the tax-free growth over decades, and the after-tax gap against investing the same money in a taxable brokerage account.
2026 self-only limit is $4,400; family is $8,300. Age 55+ adds $1,000 of catch-up.
California and New Jersey tax HSA contributions — set this to their rate for an accurate result.
Payroll contributions also escape the 7.65% FICA tax; direct contributions do not.
A stock-heavy allocation inside the HSA, not the cash sweep most custodians default to.
| Scenario | Total contributed | Tax saved per year | HSA balance | Taxable, after-tax | HSA advantage | Gap |
|---|---|---|---|---|---|---|
| 25 yrs at 7% | $207,500 | $3,042 | $561,715 | $299,611 | $262,103 | 87% |
| 20 yrs at 6% | $166,000 | $3,042 | $323,640 | $186,380 | $137,260 | 74% |
| 15 yrs at 6% ($4,400/yr) | $66,000 | $1,613 | $108,559 | $65,179 | $43,380 | 67% |
| 30 yrs at 7% | $249,000 | $3,042 | $838,906 | $425,900 | $413,006 | 97% |
The taxable comparison assumes the same dollars are contributed after paying federal and FICA tax, grow at 85% of the HSA's return (drag from tax on dividends), and are taxed at 15% long-term capital gains on withdrawal. HSA withdrawals are assumed to be qualified medical expenses.
| Point in time | Contributed | HSA balance | Growth (all tax-free) |
|---|---|---|---|
| Year 5 | $41,500 | $51,072 | $9,572 |
| Year 10 | $83,000 | $122,704 | $39,704 |
| Year 15 | $124,500 | $223,171 | $98,671 |
| Year 20 | $166,000 | $364,081 | $198,081 |
| Year 25 | $207,500 | $561,715 | $354,215 |
The growth overtakes contributions around year nine in this scenario. From that point the third tax break — tax-free withdrawal — is doing more work than the contribution deduction, which is why funding an HSA you do not spend is so much more valuable than one you drain annually.
An HSA is the only account in the U.S. tax code with no tax at any of the three stages: money goes in pre-tax, grows untaxed, and comes out untaxed for qualified medical expenses. That much is well known. What is less well understood is how unevenly the three breaks are distributed over a lifetime.
Worth your marginal federal rate plus state rate, plus 7.65% FICA if you contribute through a payroll cafeteria plan. At a 24% federal rate and 5% state, a payroll contribution saves 36.65% immediately; a direct contribution saves 29% because it misses FICA. That is the single largest argument for routing HSA dollars through payroll.
This is the break that compounds into the largest number, but only if the account is invested rather than held in cash. Most HSA custodians default the balance into a low-yield sweep account and require you to opt into investing above a cash threshold. A 25-year contribution stream at 7% produces $561,715 on $207,500 of contributions — at 0.5% in a cash account it produces barely more than the contributions themselves.
Qualified medical expenses are tax-free at any age, and there is no lifetime cap and no requirement to take distributions. Non-qualified withdrawals before 65 are taxable plus a 20% penalty; after 65 they are taxable but penalty-free, which makes a mature HSA function as a de facto traditional IRA in the worst case.
There is no deadline for reimbursing yourself from an HSA. Pay medical costs out of pocket now, keep the receipts, and reimburse yourself years later — the HSA grows tax-free in the meantime and the eventual withdrawal is still qualified. This is the mechanism that turns an HSA into the most tax-efficient retirement account available, and it is why the balance figures here assume you never spend the account.
The contribution deduction is a fixed percentage of each dollar you put in — 29% or 36.65% depending on how you fund it. It does not compound. The growth break does. In the base scenario the contribution deduction is worth $3,042 a year, but by year 25 the tax-free growth alone has added more than $350,000 that would otherwise have been taxed.
The taxable comparison in this calculator is deliberately generous to the taxable account: it assumes you only lose 15% of the return to dividend tax each year and pay 15% long-term capital gains at the end. Real taxable accounts with bond exposure or active turnover lose more. The HSA's advantage in practice tends to be larger than the modeled gap, not smaller.
The one assumption that can erase the advantage is spending the balance every year. An HSA used as a pass-through for current medical bills captures only the contribution deduction — still worth 29%-36.65%, but a fraction of the long-run value of an invested, untouched account.
Contributions are deductible (or pre-tax through payroll), growth is tax-free, and withdrawals for qualified medical expenses are tax-free. No other U.S. account offers all three; a traditional IRA misses the third, and a Roth misses the first.
In this calculator's base case — $8,300 a year at a 24% federal and 5% state rate for 25 years at 7% — the HSA finishes about $262,000 ahead of the same money in a taxable account, roughly 87% more after capital gains tax.
Invest it, if you can cover your deductible out of pocket from other savings. The cash sweep at most custodians earns under 1%, and the tax-free growth break is worthless on a balance that does not grow.
Before age 65 it is taxable income plus a 20% penalty. After 65 the penalty disappears and it is taxed like a traditional IRA distribution — so you never face a worse outcome than an ordinary pre-tax retirement account.
Yes, as long as the expense was incurred after the HSA was established and you have documentation. There is no time limit, which is what makes paying out of pocket and reimbursing decades later a legitimate strategy.
Payroll HSA contributions escape FICA, so they do slightly reduce your reported earnings for Social Security. For most people the immediate 7.65% saving is worth far more than the marginal effect on future benefits.
⚠️ Important: This calculator models federal and state income tax only, using the marginal rates you enter, and assumes all HSA withdrawals are for qualified medical expenses. It does not account for California and New Jersey state taxation of HSA growth, custodian fees, contribution pro-rating for partial-year eligibility, or the interaction of a payroll contribution with the Social Security wage base. Investment returns are hypothetical.