The HSA Is the Most Tax Favored Account You Probably Own

A health savings account is usually sold as a way to pay this year’s medical bills with pre-tax money. That is the smallest thing it does. The Internal Revenue Service treats an HSA differently from every other account in the code: contributions are deductible, earnings accumulate untaxed, and distributions for qualified medical expenses come out tax free. Nothing else in American personal finance does all three.

The complications are real, though, and they arrive in a specific order. The account is only open to people in a particular kind of health plan. The rules for leaving it are unforgiving. And the strategy that turns it into a retirement account requires spare cash that many households simply do not have. All three deserve attention before you decide how much to put in.

The tax breaks, stated precisely

The deduction comes first, and it is more generous than most deductions. IRS Publication 969 states that you can claim a deduction for contributions you or someone other than your employer makes to your HSA even if you do not itemize on Schedule A. That puts it in a small category of write-offs available to the roughly nine in ten filers who take the standard deduction.

The second break is the absence of tax on growth. Interest, dividends and capital gains inside the account are not taxed as they accrue, which is the same treatment a Roth IRA gets.

The third is the one no other account offers: qualified withdrawals are tax free. Publication 969 points to Publication 502 for the definition of a qualified medical expense, and the list is broad, covering diagnosis, cure, mitigation, treatment or prevention of disease.

There is a fourth advantage that almost never gets mentioned, and it is available only through payroll. Publication 969 notes that employer contributions, which include amounts you route through a cafeteria plan, are generally not subject to employment taxes. The employee share of those taxes is 6.2 percent for Social Security and 1.45 percent for Medicare, 7.65 percent combined up to the Social Security wage base, which is 184,500 dollars for 2026. On a 4,400 dollar contribution, routing it through payroll rather than writing a cheque to the custodian and deducting it later is worth about 337 dollars in avoided payroll tax, before any income tax saving at all.

That is the single easiest hundreds of dollars in this article, and it costs nothing but filling in a form at work.

Eligibility is narrower than the marketing suggests

Publication 969 sets four conditions. You must be covered by a qualifying high deductible health plan on the first day of the month, you must have no other disqualifying health coverage, you must not be enrolled in Medicare, and you must not be claimable as a dependent on someone else’s return.

The second condition catches people. A general purpose health flexible spending account disqualifies you, and so does your spouse’s general purpose FSA, because it can reimburse your expenses. A second health plan through a spouse’s employer does the same thing.

What counts as a qualifying plan is defined by four numbers, all of which move each year. The 2026 figures come from Publication 969; the 2027 figures were set in Revenue Procedure 2026-24.

Notice the row that does not move. The age 55 additional contribution is fixed at 1,000 dollars in statute and is not indexed to inflation, so it quietly loses value every year while every other figure climbs. Note also that it is a per-person amount attached to a person, not a plan: a married couple who are both 55 or older need two separate HSAs to use both catch-ups, even if they are covered by one family plan.

What the money can buy, and the premium exception

Publication 969 is blunt that you may not use HSA funds to pay for insurance, and then lists four exceptions: long term care insurance, health care continuation coverage such as COBRA, health care coverage while you are receiving unemployment compensation, and Medicare and other health coverage if you were 65 or older, other than premiums for a Medicare supplemental policy such as Medigap.

That last exception is more useful than it looks. Once you enrol in Medicare you may no longer contribute to an HSA, but you may still spend the balance, and Part B and Part D premiums become qualified expenses. A balance built during working years can pay a decade of Medicare premiums tax free. Medigap is specifically excluded, which is an odd line to draw but a firm one.

Spend the money on something that is not a qualified expense and Publication 969 imposes an additional 20 percent tax on that portion, on top of ordinary income tax. That additional tax disappears after you become disabled, reach age 65, or die. From 65 onward, an HSA used for non-medical purposes behaves like a traditional IRA: taxable, but not penalised. That is the account’s floor, and it is a reasonable one.

The strategy that changes the account’s job

The advice you will read everywhere is to stop treating the HSA as a debit card, pay routine medical bills out of pocket, and let the balance compound. That advice is sound. It is also more expensive than it sounds, and the size of both the benefit and the cost is worth working out rather than assuming.

Take a household contributing the 2026 self-only maximum of 4,400 dollars a year for 20 years, with 1,500 dollars of out-of-pocket medical costs annually, assuming a 6 percent average annual return, contributions and withdrawals at year end, and the contribution held flat rather than indexed upward.

The second column is worth about 55,200 dollars more after 20 years. It also required 30,000 dollars of after-tax money found somewhere else, 1,500 dollars a year, every year, without exception. That is a genuine trade, not free money, and it is only a good trade for a household that can make those payments without reaching for a credit card. Paying a 1,500 dollar medical bill on a card at 22 percent in order to protect a balance compounding at 6 percent is a losing move dressed up as a strategy.

The returns above are an assumption, not a promise. Markets do not deliver 6 percent on a schedule, and a bad first decade changes these numbers considerably.

The receipt rule, in the IRS’s own words

The part of this that sounds too good to be true is documented, and the citation is worth knowing. IRS Notice 2004-50, question 39, addresses whether a distribution must be taken in the year an expense is incurred. It states that an account beneficiary may defer to later taxable years distributions to pay or reimburse qualified medical expenses incurred in the current year, as long as the expenses were incurred after the HSA was established, and that there is no time limit on when the distribution must occur.

So a dental bill you pay out of pocket in 2026 can be reimbursed from the HSA in 2046, after the balance has grown for two decades, with no tax on the growth. The receipts function as vouchers for tax free withdrawals at a time of your choosing.

Two conditions do real work here. The expense must be incurred after the account was established, which makes the establishment date of your first HSA a genuinely valuable thing to lock in early, even with a small deposit. And the same notice requires you to keep records sufficient to show the distributions were exclusively for qualified medical expenses not previously reimbursed and not taken as an itemised deduction.

That record-keeping obligation runs for decades and sits entirely with you. A receipt you cannot produce is worth nothing. If you intend to use this strategy, the filing system is not an afterthought; it is the strategy. Scan everything, store it in two places, and keep a running total so that the future withdrawal is a lookup rather than an archaeology project.

Four ways this goes wrong

Medicare timing. Publication 969 states that beginning with the first month you are enrolled in Medicare, your contribution limit is zero. Because enrolment can reach backward, Medicare’s own guidance is that you and your employer should stop contributing to an HSA six months before you retire or apply for Social Security benefits, in order to avoid a tax penalty. Six months, not one. This is the single most common expensive mistake made by people working past 65.

The last-month rule and its testing period. If you are eligible on 1 December, Publication 969 treats you as eligible for the whole year, which lets someone who joined an HDHP in October contribute a full year’s limit. The catch is the testing period, which runs from that December through the last day of the twelfth month following, for example 1 December 2025 through 31 December 2026. Fail to remain eligible during that window, for any reason other than death or disability, and you must include in income the contributions that would not have been possible without the rule, plus a 10 percent additional tax. Changing jobs to an employer with a traditional plan is enough to trigger it.

Beneficiary designation. Publication 969 is stark on this. If your spouse is the designated beneficiary, the account is treated as your spouse’s HSA after your death and everything continues. If anyone else is the beneficiary, the account stops being an HSA and its fair market value becomes taxable to that beneficiary in the year you die, reduced only by qualified expenses of yours they pay within one year. A six-figure HSA left to an adult child is a six-figure taxable event in a single year. Check who is named.

Custodian friction. Many HSA providers require a minimum cash balance before you may invest anything, and charge a monthly administrative fee. On a 1,200 dollar balance, a three dollar monthly fee is three percent a year, which will comfortably outrun the tax advantage. Check the fee schedule and the investment threshold before assuming the compounding story applies to your account.

A decision rule

In order, because the order matters:

1. Judge the health plan before you judge the account. Add a full year of premiums to the plan’s out-of-pocket maximum. That is your worst case. Compare worst cases across the plans on offer, then compare the likely case, then subtract any employer HSA contribution from the HDHP side. If the HDHP still loses, the tax advantage does not rescue it.
2. Open an HSA the first year you are eligible, even with a token deposit. The establishment date determines which future expenses can ever be reimbursed.
3. Contribute through payroll. That is where the 7.65 percent payroll tax saving lives, and it is not available on contributions you make directly.
4. Hold cash equal to your deductible, invest the rest. This gives you a reason not to sell investments at a bad moment to cover a hospital bill.
5. Pay current bills out of pocket only when you can do so without borrowing. Otherwise use the account for what it was designed for and take the still-considerable tax break.
6. Keep every receipt, in one place, backed up. Add a note of the date and amount so the file is usable in twenty years.
7. Name your spouse as beneficiary if you have one, and revisit after any life change.
8. Stop contributing six months before you apply for Social Security.

The limitation nobody advertises

The HSA rewards people who can afford not to use it. Every advantage described above scales with the ability to leave the money alone, which means the account delivers most to the households that need it least. A family that hits its deductible most years, has no spare cash flow, and chose the high deductible plan because it was the cheapest premium on the menu will get the deduction and very little else. For them the triple tax advantage is largely theoretical, and the honest answer is that the low deductible plan may have been the better choice regardless of what the account could have done.

That is not an argument against HSAs. It is an argument for checking which household you are before deciding how hard to chase the strategy.

General information, current as of September 2026, and not personalised financial or tax advice. Contribution limits, plan thresholds and tax rules change annually; check the primary sources above before acting on anything with money attached.