HSA Calculator

A Health Savings Account (HSA) is a tax-advantaged savings account designed for people enrolled in a High-Deductible Health Plan (HDHP). Unlike a Flexible Spending Account (FSA), HSA funds roll over indefinitely — there is no "use it or lose it" rule. This makes the HSA one of the most powerful wealth-building tools available in the U.S. tax code, especially for those who can afford to let it grow untouched until retirement.

To contribute to an HSA in 2024, you must be covered under a qualifying HDHP, not enrolled in Medicare, and not claimed as a dependent on someone else's return. The IRS sets annual contribution limits — $4,150 for self-only coverage and $8,300 for family coverage in 2024. Account holders aged 55 or older may make an additional catch-up contribution of $1,000 per year.

Contributions can come from you, your employer, or both — but the combined total cannot exceed the annual IRS limit. Employer contributions count toward your limit and are excluded from your gross income. Funds in the account can be invested in mutual funds, ETFs, stocks, and other instruments once a threshold balance is met, allowing your HSA to grow like a retirement account over time.

Withdrawals for qualified medical expenses are always tax-free at any age. After age 65, non-medical withdrawals are treated just like traditional IRA withdrawals — taxed as ordinary income but penalty-free. This flexibility makes the HSA uniquely versatile: it is simultaneously a health savings vehicle, an investment account, and a retirement supplement.

This HSA calculator uses monthly compounding to project your account balance at retirement. Each month, your existing balance earns a return equal to one-twelfth of your annual expected return rate, and one-twelfth of your net annual contribution is added. This mirrors how real investment accounts compound returns continuously throughout the year rather than only once annually.

The net annual contribution used in each year is the sum of your personal contribution (capped at the IRS maximum), any applicable catch-up contribution if you are 55 or older, and your employer's contribution. If you choose to pay medical expenses directly from your HSA, those withdrawals reduce the net contribution each year, resulting in a lower projected balance but providing immediate tax-free healthcare spending.

The calculator iterates month by month across every year from your current age to your retirement age, applying growth and contributions simultaneously. This makes the projection more accurate than simple end-of-year lump-sum approximations.

The HSA's signature benefit is its triple tax advantage — a combination not available in any other account type. The calculator breaks this advantage into three distinct components so you can see exactly how much each one saves you over your investment horizon.

1. Tax-Deductible Contributions

Every dollar you contribute to your HSA reduces your federal taxable income dollar-for-dollar. If you are in the 24% tax bracket and contribute $3,850, you save $924 in federal income taxes that year. The calculator sums this saving across every year from now to retirement, accounting for the additional $1,000 catch-up contribution once you reach age 55.

2. FICA Tax Savings

When contributions are made through a payroll deduction plan, they also escape FICA taxes (Social Security and Medicare taxes). The combined employee FICA rate is 7.65%. This is money saved on top of income-tax deductions — a benefit the 401(k) does not offer for employee contributions. The calculator applies this rate to all employee contributions made during the projection period.

3. Tax-Free Investment Growth

Your HSA investments grow completely free of capital gains taxes, dividends taxes, and interest taxes. When you eventually withdraw for qualified medical expenses, that growth is never taxed at all. The calculator quantifies this benefit by applying your marginal tax rate to total investment earnings — representing the tax you would have paid in a standard taxable brokerage account.

Together, these three components can add up to tens of thousands of dollars in lifetime tax savings. For a 35-year-old in the 24% bracket who contributes $3,850 per year and earns 6% annually for 30 years, the total tax advantage can easily exceed $60,000.

Most financial advisors recommend treating your HSA as a stealth retirement account — paying current medical expenses out of pocket whenever possible and letting the HSA balance compound untouched. This strategy, sometimes called "receipts banking," involves saving your medical receipts and reimbursing yourself years or even decades later, allowing the money to grow tax-free in the meantime. There is no time limit on HSA reimbursements for qualified expenses already paid out of pocket.

When choosing investments inside your HSA, consider a low-cost index fund strategy similar to what you would use in a Roth IRA. Because HSA withdrawals for qualified medical expenses are tax-free regardless of account gains, the HSA is actually the best account to hold high-growth assets — outranking even the Roth IRA for healthcare spending. A common portfolio allocation for long-horizon HSA investors is a diversified equity index fund during the accumulation phase, gradually shifting toward bonds and stable-value funds as retirement approaches.

Many HSA providers require a minimum cash balance (often $1,000 to $2,000) before you can invest the rest. Check your plan's investment options and fee structure. Some employers offer HSAs through custodians with limited or high-fee fund choices — in that case, it may be worth rolling the HSA to a lower-cost provider after leaving the employer.

The expected return you enter in this calculator should reflect a realistic long-term investment return. Historically, a diversified stock index portfolio has returned roughly 7–10% annually before inflation. A conservative assumption of 5–7% is commonly used for planning purposes, while a portfolio kept entirely in cash or money market funds may earn only 1–4%.

Healthcare is consistently one of the largest expenses in retirement. Fidelity's annual retiree health care cost estimate suggests an average retired couple may need over $300,000 in today's dollars to cover healthcare costs in retirement. Your HSA balance can be a critical source of tax-free funding for these costs.

After age 65, your HSA becomes even more flexible. You can withdraw funds for any reason — not just medical expenses. Non-medical withdrawals after 65 are taxed as ordinary income (like a traditional IRA) but are not subject to the 20% early withdrawal penalty that applies before 65. For medical expenses — including Medicare premiums (Parts B, C, and D), dental, vision, hearing aids, and long-term care insurance premiums — withdrawals remain completely tax-free at any age.

If you are approaching retirement with a large HSA balance, consider using it as your primary source for healthcare costs while directing other savings (401k, IRA) toward living expenses. This sequencing maximizes the tax advantage and can meaningfully reduce your overall retirement tax burden. An HSA can also work in coordination with a Health Reimbursement Arrangement (HRA) or Medicare Supplement plan.

Note that once you enroll in Medicare, you can no longer contribute to an HSA — but you can continue to use the existing balance tax-free for qualified expenses indefinitely. Plan your last year of HSA contributions carefully around your Medicare enrollment date to avoid excess contribution penalties.