What should your idle HSA cash actually be earning? Type two numbers and find out.
How to use this: open your HSA's rate page, find the APY on cash, and enter it above. The red row is what a neglected bank HSA pays; the highlighted row is the best tier we could verify this month. The gap between those two rows is the money you're leaving on the table — tax-free, every year, on money that's already yours.
Interest at rate r on balance B, compounded monthly for one year: B × ((1 + r/12)12 − 1). For everyday rates the simple version (B × r) is within a few cents. Three-year figures assume monthly compounding with no contributions — every dollar of interest in an HSA is also tax-free, which is the part people forget: to earn the same after tax in a normal savings account at 22% marginal rate, you'd need roughly 1.28× the stated APY.
Every verified provider rate in one place.
The after-tax comparison that changes the answer.
$4,400 / $8,750 / $1,000 catch-up.
Why the rate isn't automatic — and when it's taxable.
What your FSA dollars can buy before the deadline.
December 31, March 15, or carryover — know which one is yours.