HSA vs High-Yield Savings Account
The HYSA advertises 4%+. Your HSA advertises 0.05%. The HSA can still win — here's the after-tax math that decides it.
On pure interest, a high-yield savings account beats almost every HSA cash rate. But HSA interest is never taxed — federal or state — and HSA contributions dodge income tax and payroll tax on the way in. For money you'll spend on healthcare anyway, a modest HSA rate can beat a big HYSA rate after tax.
The after-tax comparison
Assume a 24% marginal federal rate, a 4.35% HYSA, and the verified Fidelity HSA sweep at 1.96%:
| HYSA at 4.35% | HSA at 1.96% |
|---|
| Stated rate | 4.35% | 1.96% |
| Federal tax on interest | −1.04% | $0 |
| State tax on interest (example 5%) | −0.22% | $0 |
| After-tax yield | ≈ 3.09% | 1.96% |
On savings interest alone the HYSA still wins — if the HSA's cash rate is only ~2%. The HSA pulls ahead through the contribution side:
- Money into the HSA skips federal income tax and the 7.65% FICA payroll tax (through a cafeteria plan at work). A 4.4% family contribution is pre-tax dollars the HYSA never sees.
- Growth is tax-free, and withdrawals for qualified medical expenses are tax-free. The HYSA's 3.09% after-tax is its ceiling; the HSA's return compounds untaxed forever.
- Invested HSA dollars historically out-earn any savings account. Once you can invest inside the HSA, the comparison isn't 1.96% vs 4.35% — it's market returns vs 3.09%, tax-free vs taxed.
The three catches that flip it back
- An HSA requires an HDHP. No high-deductible health plan, no HSA, period. The HYSA accepts everyone.
- HSA withdrawals for non-medical use before 65 are taxed plus a 20% penalty. A savings account never punishes you for taking your own money out.
- Cash in a bad HSA earns almost nothing. If your employer's HSA pays 0.01%, the honest comparison is 0.01% vs 3.09% — and the HYSA wins on every dollar you might need short-term. The fix is a better custodian (see the 2026 ranking), not giving up.
Rule of thumb: keep this year's likely medical spending in the best-rate cash you can find — then put every dollar beyond that into the HSA and invest it.
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Rate figures verified October 2026 (see
main table for sources) · Tax rules:
IRS Pub 969. Tax rates in the example are illustrative — your marginal rate and state tax change the arithmetic, not the conclusion. Not tax or financial advice.