HSA Calculator (Triple Tax Advantage & Growth to 65)

Three tax breaks in one account

An HSA is the only mainstream account that wins at every stage. Money goes in untaxed (deductible, or pre-tax through payroll). It grows untaxed: no tax on interest, dividends, or gains along the way. And it comes out untaxed too, as long as the withdrawal pays for qualified medical expenses. Every other tax-advantaged account makes you pick a side, taxed now or taxed later; the HSA skips both, which is why people who can afford to invest theirs treat it as a first-class retirement vehicle rather than a medical checking account.

What the projection assumes

The math is straightforward compounding: your balance grows at the return you set, and each year's contribution lands at year-end. Contributions are capped at the current annual limit for your coverage type, and the tax-saved stat is simply your contribution multiplied by your marginal rate, an educational approximation of the income tax that contribution avoids this year. The projection holds today's limit constant; in reality limits tend to drift upward with inflation, so long horizons are, if anything, understated.

Worked example: self-only coverage for 25 years

Someone contributes the 2026 self-only limit of $4,400 every year, starting from a $3,000 balance, invested at 6%. After 25 years they arrive at 65 with about $254,279, of which only $113,000 was contributed; the rest is untaxed growth. Along the way, each year's contribution saves roughly $1,056 of income tax at a 24% marginal rate, before counting any payroll-tax savings from contributing through work.

The stealth retirement account move

After 65, an HSA quietly becomes a second 401(k): non-medical withdrawals lose the penalty and are just taxed as ordinary income, while medical spending stays tax-free for life, and healthcare is one of retirement's largest bills anyway. The power move many savers use: pay today's medical costs out of pocket, keep the receipts, and let the HSA compound untouched. Reimbursement has no deadline, so decades-old receipts can be cashed in tax-free whenever you want the money. This matters most if you are already capturing an employer match elsewhere; see the retirement calculator for how the pieces add up across accounts.