How to actually use your HSA — the triple-tax math
The HSA is the only triple-tax-advantaged account in the US: pre-tax in, tax-free growth, tax-free withdrawal for medical. Compare three strategies — spend-as-you-go, stealth Roth, or skip HSA entirely — to see which builds the most retirement wealth on your numbers.
How to use this in 60 seconds
- Confirm you have an HSA-eligible plan — only HDHPs (high-deductible plans meeting IRS minimums) qualify. If you're on a traditional plan or HMO, the HSA option isn't available regardless of which strategy "wins" mathematically.
- Set your annual contribution at the limit — $4,300 self-only or $8,550 family in 2025. The triple-tax-advantage math only works if you actually fund the account.
- Look at the green-highlighted winner card — for most long horizons it's the stealth Roth. If your horizon is short or your medical spend is large vs the contribution limit, spend-as-you-go can win instead.
The stealth Roth play, explained
The HSA gets called "triple-tax-advantaged" because three things happen:
- Pre-tax contribution — federal income tax + FICA + state (in most states) all skipped on the way in.
- Tax-free growth — no taxes on dividends, interest, or capital gains while invested.
- Tax-free withdrawal for qualified medical — no taxes coming out, ever, if used for medical.
The "stealth Roth" trick: instead of using HSA dollars for current medical (which spends them), you pay medical out of pocket from a taxable account, leave the HSA invested for decades, and save the medical receipts. IRS rules let you withdraw against any HSA-qualified expense from any prior year, with no statute of limitations.
In retirement, you withdraw the entire HSA balance tax-free against your accumulated receipts. The HSA effectively becomes a Roth IRA with extra steps — and the contribution limits stack independently of regular IRA limits.
Math runs in your browser. We don't store your inputs. Source on github.
Where this framework breaks
- HDHP premium tradeoff is unmodeled. If your HDHP costs $200/mo more in premium than a traditional plan, that's $2,400/yr offsetting the HSA tax savings. Make sure the math still works after accounting for premium difference.
- Receipt-keeping is required. The stealth Roth strategy depends on saving every medical receipt. Use a digital scan + cloud backup. If you lose them, the excess balance gets taxed as ordinary income at retirement.
- State exceptions. California and New Jersey tax HSA contributions and earnings at the state level. The federal triple-tax math still works, but the state component is missing.
- Death of HSA owner. Spousal inheritance preserves HSA status. Non-spousal inheritance collapses the entire balance into ordinary income for the heir in the year of death. Estate planning matters.