HSAs are arguably the most tax-advantaged account in US personal finance, pre-tax in, tax-free growth, tax-free medical withdrawals.
HSA balance at retirement
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Annual tax savings (this year)
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Federal + state + FICA on payroll deduction.
Lifetime tax savings (contributions)
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Worked example
Suppose you start with a $5,000 HSA balance, contribute $8,750 a year through payroll, earn 7% a year, sit in a 32% marginal tax bracket, and let it grow for 30 years. Each year the tool adds your $8,750 and grows the balance by 7%, the same triple-tax-advantaged compounding that makes the HSA so powerful: money goes in pre-tax, grows tax-free, and comes out tax-free for medical costs. After 30 years the account reaches about $922,450. The yearly tax saving on a payroll contribution is the contribution times your marginal rate plus the 7.65% FICA you also avoid when you contribute through payroll, so $8,750 times 39.65% is about $3,469 a year. Over 30 years those upfront tax savings add up to roughly $104,081, on top of about $262,500 of contributions. That combination of immediate tax savings and decades of untaxed growth is why many savers treat a maxed HSA as a stealth retirement account.
| Item | Amount |
|---|---|
| Starting balance | $5,000 |
| Annual contribution | $8,750 |
| Total contributed (30 yr) | $262,500 |
| Annual tax savings (32% + 7.65% FICA) | $3,469 |
| Lifetime tax savings | $104,081 |
| Balance after 30 years (7%) | $922,450 |
How it is calculated
The balance projection runs year by year. Each year it adds your annual contribution, then multiplies the whole balance by one plus your assumed return, so contributions and prior growth both compound. The tax savings figure reflects the deduction on the way in. A contribution made through payroll avoids federal income tax, state income tax where it applies, and the 7.65% Social Security and Medicare payroll tax, so the tool multiplies your contribution by your marginal rate plus 7.65% to estimate the yearly saving, and multiplies that by the number of years for the lifetime figure. Contributions made outside payroll, by contrast, still save income tax but not the FICA portion. The growth shown assumes you invest the HSA rather than leave it in cash, and the projection ignores account fees and any withdrawals for current medical expenses, which would lower the ending balance. Used for qualified medical costs, withdrawals are tax-free, which is what completes the triple tax advantage.