You can invest every dollar in your HSA above whatever cash minimum your custodian requires, and at some providers that minimum is zero. The federal government caps what you can put into the account each year (for 2026, $4,400 for self-only coverage and $8,750 for family coverage1Internal Revenue Service. IRS Notice 2026-05 – Expanded Availability of Health Savings Accounts Under the OBBBA), but it doesn’t cap what share of the balance you can move into investments. That decision belongs to your custodian.
The Cash Minimum Is the Real Gate
Most HSA providers split your account into two buckets: a cash portion that behaves like a checking account, and an investment portion that behaves like a brokerage. Many of them require you to keep a minimum balance in the cash bucket before they’ll let you invest anything at all. That threshold isn’t set by federal law. It’s a contractual term written into your account agreement, and it varies widely.
Some providers charge no minimum. Fidelity, for one, has no required cash balance and no account fees on its self-directed HSA brokerage option.2Fidelity Investments. HSA Investment Options Others hold back $1,000, $2,000, or as much as $3,000 in cash before the investment window opens. The only reliable way to find your number is to read your custodian’s disclosure or log into your account and look for the “available to invest” figure.
The math is simple once you know the threshold. If your balance is $6,000 and the required cash floor is $2,000, you can invest $4,000. If the floor is zero, you can invest the whole $6,000. That single variable governs more of your long-term HSA growth than almost anything else in the account, because the cash bucket typically earns very little. A $2,000 cash floor earning 0.1% interest instead of an 8% average market return costs roughly $160 per year in lost growth, and that gap compounds each year the money sits there.
Why the Uninvested Portion Costs You
The HSA is the only account in the tax code that offers three tax advantages at once: contributions reduce your taxable income, investment growth inside the account is untaxed, and qualified medical withdrawals come out tax-free.3Internal Revenue Service. Publication 969, Health Savings Accounts and Other Tax-Favored Health Plans A traditional 401(k) taxes you on the way out. A Roth IRA taxes you on the way in. An HSA used for medical expenses does neither, and shelters the growth in between.
That’s why cash sitting idle in an HSA is a bigger loss than cash sitting idle in a regular savings account. You’re giving up not just the returns, but the tax-free compounding on those returns.
Moving Cash Into Investments
Once you know your available-to-invest figure, the mechanics are straightforward. Log into your HSA portal and find the investment or brokerage section. Most platforms display the amount you can move (your total cash minus the required minimum), and from there you pick funds or securities and confirm the trade. Settlement typically takes one to two business days.
Two features are worth turning on if your provider offers them:
- Automatic sweeps. You set a trigger so any cash above a chosen level moves into your investments on its own. This keeps new contributions and reimbursements from piling up in the low-yield bucket.
- Target-date or model portfolios. If you’d rather not pick individual funds, most platforms offer prebuilt allocations by risk tolerance or time horizon.
If Your Custodian’s Minimum Is Too High, Switch
You aren’t stuck with the HSA your employer picked. You can move your balance to a different custodian at any time, and the cleanest way is a direct trustee-to-trustee transfer: your old provider wires the money to your new one. There’s no tax consequence, no reporting headache, and no cap on how often you can do it.4Internal Revenue Service. Rollovers of Retirement Plan and IRA Distributions
The other option, a 60-day rollover, has you take the distribution and redeposit it yourself within 60 days. You’re limited to one of those every 12 months, and blowing the deadline turns the whole amount into a taxable distribution with penalties. Direct transfer is the safer route.
What You Can Actually Invest In
Most custodians offer a menu of mutual funds and ETFs covering domestic stocks, international stocks, and bonds. Some add individual stocks or a self-directed brokerage window. The range at employer-selected providers is often narrower than at direct-to-consumer platforms.
Federal law puts a few things off-limits. HSA assets can’t be invested in life insurance contracts.5Office of the Law Revision Counsel. 26 USC 223 Health Savings Accounts Collectibles are also prohibited: artwork, antiques, gems, stamps, most coins, rugs, and alcoholic beverages. There’s a narrow exception for certain government-minted bullion held by the trustee. If you buy a prohibited collectible through the account, the IRS treats the purchase as a taxable distribution.6Office of the Law Revision Counsel. 26 USC 408 Individual Retirement Accounts Most people never run into these rules because custodian platforms don’t list prohibited assets in the first place.
Fees That Shrink the Invested Share
Anything a fee takes is money that never grows tax-free. Three fee categories are worth checking:
- Monthly maintenance fees on the investment sub-account. These are often waived above a certain balance and can range from nothing to a few dollars a month.
- Advisory fees on managed or robo-advisor options. Fidelity charges nothing on managed HSA balances under $25,000 and 0.35% annually above that.2Fidelity Investments. HSA Investment Options
- Fund expense ratios inside the mutual funds and ETFs you pick. An index fund might run 0.03% a year; an actively managed fund can be 0.50% or higher.
The difference between a high-fee and low-fee provider compounds over decades. If your employer’s HSA carries meaningful fees or a limited menu, a trustee-to-trustee transfer to a lower-cost custodian is usually one of the easiest financial improvements available.
The Contribution Ceiling
Custodian rules govern how much of your existing balance gets invested. Federal law governs how much can enter the account in the first place. For 2026, the annual contribution limits are:
- Self-only coverage: $4,400
- Family coverage: $8,750
Those figures come from IRS Notice 2026-05 and reflect the inflation-adjusted amounts under Internal Revenue Code Section 223.1Internal Revenue Service. IRS Notice 2026-05 – Expanded Availability of Health Savings Accounts Under the OBBBA If you’re 55 or older, you can add $1,000 on top as a catch-up contribution.5Office of the Law Revision Counsel. 26 USC 223 Health Savings Accounts That catch-up figure is written into the statute and doesn’t index for inflation; it’s been $1,000 since 2009.
Contributing over the limit triggers a 6% excise tax for every year the excess stays in the account.7Office of the Law Revision Counsel. 26 USC 4973 Tax on Excess Contributions to Certain Tax-Favored Accounts and Annuities You can avoid the penalty by withdrawing the excess (and any earnings on it) before your tax filing deadline, including extensions. Miss that window and the 6% keeps compounding each year until you fix it.
Between the annual limit above and the custodian’s cash floor below, everything in the middle is available to invest. Knowing both numbers, and reading your custodian agreement to confirm the floor, is what turns an HSA from a healthcare checking account into a long-term investment vehicle.