HSA Rules: Contribution Limits, Investment Options, and the Triple Tax Advantage

The Only Account That Escapes Taxes Three Separate Times

In 2023, Americans held approximately $116 billion in health savings accounts—a figure that has roughly tripled over a decade. The growth reflects dawning recognition of what tax attorneys have known since HSAs were created by the Medicare Prescription Drug, Improvement, and Modernization Act of 2003: no other account in the U.S. tax code offers contributions that are pre-tax, growth that is tax-free, and withdrawals that are tax-free, all simultaneously. A 401(k) only gets the first. A Roth IRA only gets the last two. The HSA gets all three—but only under specific conditions that trip up millions of eligible Americans who fail to optimize the account.

The rules are strict. Miss one, and the advantage collapses.

HDHP Eligibility Requirements

To contribute to an HSA, you must be enrolled in a High-Deductible Health Plan (HDHP) as defined by IRS rules—not just any plan with a high deductible. For 2024, the IRS requires:

• Minimum annual deductible: $1,600 (self-only) / $3,200 (family)
• Maximum out-of-pocket limit: $8,050 (self-only) / $16,100 (family)
• The plan must not cover any non-preventive service before the deductible is met (with limited exceptions for certain chronic conditions under post-2019 IRS guidance)

You cannot contribute to an HSA if you are enrolled in Medicare, claimed as a dependent on someone else's tax return, or covered by a non-HDHP health plan—including a general-purpose FSA through your spouse's employer.

2024 Contribution Limits

The IRS adjusts HSA contribution limits annually for inflation. For 2024:

• Self-only HDHP coverage: $4,150
• Family HDHP coverage: $8,300
• Catch-up contribution (age 55+): additional $1,000

Contributions can be made by the account holder, an employer, or any third party on the account holder's behalf—the combined total simply cannot exceed the annual limit. Employer contributions count toward the limit. Contributions are deductible above-the-line regardless of whether the taxpayer itemizes, one of the few remaining above-the-line deductions available to most Americans.

HSA vs FSA vs HRA: A Direct Comparison

Investment Options and the Custodian Difference

Most HSA custodians require a minimum cash balance—typically $1,000 to $2,000—before allowing funds to be invested in mutual funds or other securities. The range of available investments varies enormously by custodian. Fidelity's HSA offers commission-free mutual funds and ETFs with no investment threshold and no monthly fees. Optum Bank, one of the largest HSA custodians by assets, offers a more limited fund menu with higher fees. Lively, a newer entrant, offers no monthly fees and a Charles Schwab brokerage integration.

Fees matter enormously. A $50 annual fee on a $5,000 balance represents a 1% drag on returns annually—equivalent to a costly mutual fund expense ratio before even counting the fund's own costs.

The Stealth IRA Strategy

The most powerful HSA strategy, sometimes called the "stealth IRA" or "mega backdoor HSA," involves paying current medical expenses out-of-pocket and preserving HSA funds for long-term investment growth. The IRS does not require you to reimburse medical expenses in the same year they are incurred—there is no statute of limitations on HSA reimbursements as long as the expenses occurred after the HSA was established and were qualified medical expenses at the time. A person who pays $15,000 in out-of-pocket medical costs over five years while carefully saving receipts can withdraw $15,000 from their HSA decades later—tax-free—while the remainder continues to compound.

After age 65, HSA funds can be withdrawn for any reason without penalty (though non-medical withdrawals become taxable as ordinary income, identical to a traditional IRA). This makes the HSA uniquely flexible: if you remain healthy, it functions as a supplemental retirement account with a tax advantage that matches or exceeds a traditional IRA.

Medicare and the HSA Contribution Cutoff

Medicare enrollment disqualifies an individual from making HSA contributions. This rule catches many workers who continue employer coverage past 65: Medicare Part A enrollment—which is automatic if you are already receiving Social Security benefits—retroactively covers up to six months prior to the date of application. A worker who applies for Social Security and Medicare at 65 may find that their HSA contributions for the previous six months are disqualified, triggering taxes and a 6% excise penalty on excess contributions.

Workers who delay Medicare enrollment while covered by a qualifying employer group health plan avoid this problem. Coordinating the Medicare enrollment decision with HSA contribution strategy is an important element of pre-retirement planning.

This article is for informational purposes only and does not constitute tax or financial advice. Consult a qualified tax professional regarding your specific HSA strategy and eligibility.