Interest earned inside a Health Savings Account grows completely tax-free at the federal level, provided the money is eventually spent on qualified medical expenses. That single rule separates HSA interest from interest in an ordinary savings account, where the IRS takes a bite every year. The same tax-free treatment covers investment gains on the portion of your balance you move into funds, and it holds for as long as the account stays a valid HSA.1Office of the Law Revision Counsel. 26 USC 223 – Health Savings Accounts
How the Money Actually Earns
Most custodians split an HSA into two layers. The cash side works like a savings account: interest accrues on your daily balance and is credited monthly, so it compounds. Rates on this tier are usually modest, comparable to a basic bank savings account.
The investment side is where balances can meaningfully grow. Federal law defines an HSA as a trust and allows its assets to sit in common investment funds, prohibiting only life insurance contracts and commingling with non-HSA property. In practice, most custodians let you sweep cash above a set threshold (often $1,000 or $2,000) into mutual funds or index funds. Returns depend on the funds you pick and market performance, so both the upside and the risk sit higher than on the cash tier.
Why HSA Interest Is Tax-Free
The IRS states plainly that “the interest or other earnings on the assets in the account are tax free” and that “earnings on amounts in an HSA aren’t included in your income while held in the HSA.”2Internal Revenue Service. Publication 969 – Health Savings Accounts and Other Tax-Favored Health Plans Unlike a traditional IRA, where you eventually pay ordinary income tax on withdrawals, HSA earnings are never taxed at all if you use them for qualified medical expenses.
This is the triple tax benefit. Contributions are deductible or excluded from income if made through payroll. Earnings compound tax-free inside the account. Distributions for qualified medical expenses come out tax-free.2Internal Revenue Service. Publication 969 – Health Savings Accounts and Other Tax-Favored Health Plans The underlying statute reinforces the shell itself, declaring the HSA “exempt from taxation” so long as it remains a valid health savings account.1Office of the Law Revision Counsel. 26 USC 223 – Health Savings Accounts
How It Shows Up on Your Tax Return
Because the interest lives inside a tax-exempt account, no Form 1099-INT arrives at the end of the year. Your custodian files Form 5498-SA instead, which reports the account’s year-end fair market value and your total contributions. There’s no separate breakout showing how much of the balance came from interest versus deposits.3Internal Revenue Service. Instructions for Forms 1099-SA and 5498-SA
You still file Form 8889 with your federal return if you contributed, took distributions, or inherited an HSA. It calculates your deduction, reports distributions, and determines any additional tax owed.4Internal Revenue Service. Instructions for Form 8889
How Much You Can Shelter in 2026
Only contributions up to the annual cap get the tax-favored treatment. For 2026 the IRS set the limits at:5Internal Revenue Service. Revenue Procedure 2025-19
- Self-only coverage: $4,400
- Family coverage: $8,750
- Catch-up contribution at age 55 or older: an additional $1,000
You must be enrolled in a qualifying high-deductible health plan to contribute at all. If you go over the cap, a 6% excise tax applies to the excess for every year it stays in the account. Pull the excess (and any interest it earned) out before your return’s due date, including extensions, and the penalty goes away.2Internal Revenue Service. Publication 969 – Health Savings Accounts and Other Tax-Favored Health Plans
What Determines the Rate You Earn
The rate on your cash balance tracks the broader interest rate environment with a lag. When the Federal Reserve raises the federal funds rate, HSA custodians tend to follow, though rarely in a hurry. When rates drop, the adjustment down tends to happen faster. The same dynamic shapes ordinary savings accounts.
Internally, many custodians use tiered rates. A balance under $2,000 might earn 0.01% while a balance above $10,000 earns meaningfully more. Those tiers reward larger cash positions but create a trade-off: cash parked to hit a higher tier may earn less than the same dollars would in the investment portion. The math depends on your custodian’s rate sheet and the funds you have access to.
Fees That Quietly Take the Interest Back
Fees deserve as much attention as the headline rate. On the cash side, monthly maintenance fees of $3 to $5 are common and can wipe out interest on smaller balances entirely. On the investment side, costs stack in layers: platform fees running up to $36 per year, transaction fees on fund purchases and sales, and the fund expense ratios themselves. Some providers add revenue-sharing fees that can tack on as much as 100 basis points to a fund’s effective cost.
The break-even math is unforgiving. If your cash rate is 0.10% and your monthly fee is $3.75, you need a balance above roughly $45,000 just to keep the cash tier from running a loss. For most account holders the real growth happens on the investment side, which makes scrutinizing expense ratios and platform fees the single highest-return exercise in HSA management.
What It Costs to Take the Interest Out for the Wrong Reason
Tax-free treatment only holds if the money goes toward qualified medical expenses. Withdraw for anything else and you owe ordinary income tax on the amount plus a 20% additional tax.1Office of the Law Revision Counsel. 26 USC 223 – Health Savings Accounts The penalty applies to interest and investment gains just as it does to your original contributions. A $1,000 non-qualified withdrawal in the 22% bracket loses $220 to income tax and another $200 to the penalty, handing back 42% of what came out.
The 20% penalty disappears in three situations:
- Age 65 or older. Non-medical withdrawals are still taxed as ordinary income, but no penalty applies. The HSA effectively functions like a traditional IRA for non-medical spending after that age.1Office of the Law Revision Counsel. 26 USC 223 – Health Savings Accounts
- Disability, as defined under federal tax law, regardless of age.
- Death. Distributions to a beneficiary are not subject to the 20% penalty.
The rules reward patience. If you can pay medical bills out of pocket and let the HSA compound for decades, you build a pool that stays tax-free for healthcare in retirement and penalty-free for any purpose after 65.
Moving Your HSA for a Better Rate
If another custodian offers a better cash rate, cheaper funds, or lower fees, moving the account is straightforward. A trustee-to-trustee transfer sends funds directly from one custodian to another without the money touching your hands. These transfers carry no frequency limit and no tax consequences.
A rollover works differently. Your old custodian sends you a check, and you have 60 calendar days to deposit the funds into the new HSA. You can only do one rollover in any 12-month period, and missing the 60-day window turns the entire amount into a taxable distribution subject to the 20% penalty.
When a transfer happens mid-month, the outgoing custodian should calculate interest earned through the closing date and include it in the transferred balance. Watch for transfer or account-closure fees, commonly $20 to $25, which come out of the balance before it moves. If the balance is smaller than the fee, the account closes with nothing to send. Monthly maintenance fees also keep accruing until the account officially closes, so slow paperwork can chip away at what you have.
What Happens to the Interest When You Die
Your beneficiary designation decides whether decades of tax-free growth continues or collapses into a single taxable event.
If your spouse is the named beneficiary, the HSA becomes theirs. They step in as the account holder, the tax-free status continues, and they can keep using the funds for qualified medical expenses without tax or penalty.1Office of the Law Revision Counsel. 26 USC 223 – Health Savings Accounts
If anyone other than your spouse inherits, the HSA ceases to exist as of the date of death. The full fair market value, including every dollar of accumulated interest and investment gains, becomes taxable income to that beneficiary in the year of inheritance.1Office of the Law Revision Counsel. 26 USC 223 – Health Savings Accounts A non-spouse beneficiary can reduce that taxable amount by any qualified medical expenses of the deceased they pay within one year of the death, but that’s the only offset.
Naming a spouse preserves everything the HSA was designed to do. Naming anyone else triggers a full tax hit on years of otherwise tax-free growth. On a substantial balance, that designation deserves the same attention as your retirement account beneficiaries.