Most people see a health savings account (HSA) as an easy way to pay for doctor visits, prescriptions, and other medical costs. That view is not wrong, but it is incomplete.
In practice, an HSA is one of the most tax-efficient accounts available under the U.S. tax code. For those who qualify, it offers a triple tax advantage, which no other account can match: tax-deductible contributions, tax-free growth, and tax-free withdrawals for qualified medical expenses.
When used strategically, an HSA is not just a healthcare account. It works as a supplemental retirement account with tax-free access for medical needs. In many cases, it deserves to be treated as a third tier alongside 401(k)s and IRAs.
The problem is that most people underutilize their HSAs. They contribute inconsistently, spend the balance immediately, or leave it sitting in cash — effectively neutralizing its long-term value.
This article explains how to evaluate and optimize an HSA. It covers who qualifies and why it helps support retirement planning. It also explains the mistakes that keep investors from getting full value.
Who qualifies for an HSA?
Eligibility for a health savings account is dependent on being enrolled in a qualified high-deductible health plan (HDHP). It also requires following several IRS rules.
To contribute to an HSA, you must:
- Be enrolled in a qualified high-deductible health plan.
- Not be enrolled in Medicare.
- Not be claimed as a dependent on another person’s tax return.
- Not be covered by a general-purpose flexible spending account (FSA), including certain spousal coverage arrangements.
2026 HDHP requirements
For 2026, IRS guidelines define a qualified HDHP as one that meets the following thresholds:
- Minimum deductible: $1,700 (individual), $3,400 (family)
- Maximum out-of-pocket expenses: $8,500 (individual), $17,000 (family), excluding premiums
These thresholds matter because they define the “entry point” into one of the most tax-advantaged accounts available. However, eligibility alone does not determine whether an HSA is the optimal choice. Cost trade-offs among premiums, deductibles, and expected healthcare usage are important to evaluate.
Pro tip: Lower last year’s taxable income — even after year-end
A critical planning window after age 65
For individuals working beyond age 65, HSA eligibility can continue as long as you have not elected Medicare. This creates a narrow but valuable planning window where high earners may still reduce taxable income while building tax-advantaged reserves.
When Medicare begins, HSA contributions must stop. In some cases, contributions must stop up to six months before because of Medicare’s retroactive coverage rules.
The triple tax advantage: Why the HSA is structurally unique
The HSA is the only account in the tax code that combines all three major tax advantages simultaneously.
- Tax-deductible contributions. Contributions made via payroll are typically pretax, reducing adjusted gross income (AGI). Direct contributions may also be deductible depending on filing status and circumstances.
For higher-income households, this AGI reduction can have secondary benefits beyond income tax savings, including:-
- Lower exposure to IRMAA surcharges in retirement.
- Potential reduction in net investment income tax thresholds.
- Improved control over Roth conversion tax brackets.
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- Tax-free investment growth. Within an HSA, interest, dividends, and capital gains grow free from taxation. Unlike in taxable brokerage accounts, compounding has no annual tax drag.
Over long-time horizons, this difference becomes material. Even modest annual returns compounded tax-free can create a meaningful healthcare reserve for retirement.
- Tax-free withdrawals for qualified medical expenses. Withdrawals used for qualified medical expenses are entirely tax-free, regardless of age.
This makes the HSA uniquely flexible: It can function as both a long-term investment account and a tax-free reimbursement vehicle for healthcare spending.
Comparing different accounts:
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- Traditional IRA: Tax deduction now; taxable withdrawals later
- Roth IRA: No deduction now; tax-free withdrawals later (if conditions are met)
- HSA: Tax deduction now + tax-free growth + tax-free withdrawals (for qualified medical expenses)
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Should you max out your HSA contributions?
For many investors, maximizing contributions is one of the most efficient financial moves available.
For 2026, HSA contribution limits are:
- $4,400 for individual coverage.
- $8,750 for family coverage.
- $1,000 catch-up contribution for individuals age 55 and older.
While these limits are lower than 401(k) limits, the tax structure of the HSA often makes each dollar contributed more efficient on a lifetime after-tax basis. Consistent contributions over 10-20 years when invested can compound into a substantial tax-free healthcare reserve.
Why this matters more than most investors realize
Healthcare is one of the largest and least predictable expenses in retirement. It’s estimated that a 65-year-old retiree may spend an average of $172,500 in healthcare and medical expenses throughout retirement.1 An HSA effectively creates a dedicated pool of capital designed specifically for that liability.
When maxing out may not be optimal
Despite its advantages, the HSA is not always the top priority. It may rank lower if:
- Contributing reduces the ability to capture a full employer 401(k) match.
- The HDHP results in materially higher total annual healthcare costs.
- The HSA investment platform offers limited or high-cost investment options.
- The investor is approaching Medicare eligibility and the contribution window is closing.
A rational allocation decision should compare total plan cost, tax savings, and opportunity cost — not just tax features in isolation.
The “shoebox strategy”
One of the most powerful but underused HSA strategies involves separating reimbursement from payment. Instead of using HSA funds immediately for medical expenses, many investors:
- Pay qualified medical expenses out of pocket.
- Save receipts indefinitely.
- Allow the HSA balance to remain invested and compounding.
- Reimburse themselves years or decades later, tax-free.
There is no deadline for reimbursing qualified medical expenses, provided documentation is maintained. This essentially converts the HSA into an investment account with optional tax-free liquidity.
Example
If an investor builds up $10,000 in qualified medical expenses over time, the money can remain invested. If the money stays invested for 10 to 20 years at market returns, the tax-free reimbursement can be much higher. It can exceed the original amount spent.
The key constraint is administrative discipline. Accurate recordkeeping is essential. IRS rules place the burden of proof on the account holder.
Investing inside the HSA
A common but costly mistake is treating the HSA like a checking account. Many investors leave balances in cash, forfeiting long-term growth potential. When appropriate, HSA assets can be invested similarly to retirement accounts using:
- Low-cost index funds
- Broad equity ETFs
- Diversified mutual funds
Because qualified withdrawals are tax-free, HSAs can be particularly efficient vehicles for long-term growth-oriented allocations.
The HSA in retirement: An underappreciated phase
The HSA becomes more flexible after age 65.
Before age 65
- Nonqualified withdrawals are subject to income tax plus a 20% penalty.
- Qualified medical withdrawals remain tax-free.
After age 65
- Nonmedical withdrawals are taxed as ordinary income (no penalty).
- Qualified medical withdrawals remain fully tax-free.
In effect, the HSA begins to resemble a traditional IRA with a tax-free healthcare option embedded.
What you can pay for with your HSA
In addition to common qualified medical expenses, your HSA also covers:
Medicare Part B premiums
- Medicare Advantage (Part C) premiums
- Medicare Part D premiums
- Qualified long-term care insurance premiums (subject to IRS limits)
- Dental, vision, and hearing care
- Copays, deductibles, and out-of-pocket medical costs
Important note: Medigap (Medicare supplement) premiums are not considered qualified medical expenses.
Common HSA mistakes and misconceptions
Despite its advantages, health savings accounts are often misunderstood.
“Use it or lose it”
This applies to FSAs, not HSAs. HSA balances roll over indefinitely.
Employer ownership confusion
HSAs are individually owned accounts. Employer contributions do not affect ownership.
Medicare timing errors
Contributions must stop when you enroll in Medicare. You may need to stop up to six months earlier because of retroactive coverage rules.
Spousal FSA interference
A spouse’s FSA election can unintentionally disqualify HSA contributions.
State tax treatment
State tax treatment may vary. Additionally, some states, like California and New Jersey, do not fully follow federal HSA tax rules. This may affect taxes on contributions or earnings.
Estate planning oversight
- Spouses inherit HSAs tax-free.
- Nonspouse beneficiaries generally owe income tax on the full inherited balance in the year received.
- Beneficiary designations should be coordinated with the estate plan for larger balances.
Who benefits most from an HSA?
The people who benefit from an HSA the most are:
- High-income professionals (30s-50s): Maximum benefit because of the long compounding runway and high marginal tax rates.
- Preretirees (50s-early 60s): Strong value via catch-up contributions and pre-Medicare planning window.
- Chronic healthcare users: Moderate benefit because frequent withdrawals reduce compounding.
- Medicare participants: Limited benefit; focus shifts to withdrawal strategy.
- High-balance HSA holders: Elevated estate planning considerations.
The HSA is often treated as a tactical spending tool. In reality, it is one of the most structurally advantaged accounts available in the tax code when properly used. For many households, the question is not whether they should use an HSA. It is whether they are using it in a way that aligns with its full potential.
For more information, speak with your wealth advisor and download our HSA Quick Reference Guide: Rules, Limits, and Strategies.
If you are not a Mercer Advisors client and would like to learn more.
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An HSA is not a standard savings account; it is a tax-advantaged account tied to a qualified high deductible health plan (HDHP). Unlike with a traditional savings account, contributions may be tax-deductible, investment growth is tax-free, and withdrawals for qualified medical expenses are tax-free. This combination is what creates the “triple tax advantage.”
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Yes. Most HSA providers offer investment options such as mutual funds, index funds, or ETFs after the account meets a minimum cash balance threshold. However, many account holders leave funds in cash, which limits long-term growth potential. Treating the HSA like a retirement account, rather than a spending account, is often the more efficient strategy.
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The HSA is individually owned, not employer-owned. If you change jobs, your account stays with you, along with all contributions and investment gains. You can continue using it for qualified medical expenses or keep it invested for long-term growth.
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No. Unlike flexible spending accounts (FSAs), HSAs do not have a “use it or lose it” rule. Funds roll over indefinitely and remain invested tax-free for as long as they are not withdrawn.
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You can contribute to an HSA after age 65 only if you are not enrolled in Medicare and remain covered by a qualifying high-deductible health plan. When Medicare enrollment begins, HSA contributions must stop. In some cases, contributions must be discontinued up to six months before Medicare enrollment because of retroactive coverage rules.
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Qualified medical expenses include a wide range of medical costs, such as doctor visits, prescriptions, dental and vision care, hearing aids, copays, and deductibles. After age 65, Medicare premiums (Parts B, C, and D) and qualified long-term care insurance premiums may also be eligible. However, medigap premiums are not considered qualified expenses.
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The “shoebox strategy” refers to paying medical expenses out of pocket, saving receipts, and allowing the HSA to grow invested. You can later reimburse yourself tax-free for those past qualified expenses — sometimes years later. This allows more time for tax-free compounding inside the account.
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For 2026, contribution limits are:
- $4,400 for self-only coverage.
- $8,750 for family coverage.
- $1,000 catch-up contribution for individuals age 55 and older.
These limits may adjust annually for inflation.
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After age 65, the HSA becomes more flexible. Withdrawals for nonmedical expenses are allowed without penalty but are taxed as ordinary income, similar to a traditional IRA. Qualified medical expenses remain completely tax-free, preserving the account’s core tax advantage.
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Yes. While HSAs offer strong tax benefits, they are not always the best option if:
- You forgo an employer 401(k) match to fund it.
- Your HDHP has significantly higher total healthcare costs.
- Your HSA investment options are limited or high-cost.
- You are nearing Medicare enrollment and have limited time to contribute.
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If your spouse is the beneficiary, the HSA transfers tax-free and becomes your spouse’s account. If a nonspouse inherits the HSA, the full account balance is generally treated as taxable income in the year of inheritance. Because of this, HSAs should be coordinated with estate planning for larger balances.
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Yes. After age 65, an HSA can function similarly to a traditional IRA for nonmedical withdrawals, which are taxed as ordinary income. However, its unique advantage is that qualified medical expenses — including many healthcare costs in retirement — remain completely tax-free, making it a powerful supplemental retirement resource.
1 “Fidelity Investments® Releases 2025 Retiree Health Care Cost Estimate, a Timely Reminder for All Generations to Begin Planning.” Fidelity, July 30, 2025.
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