Open enrollment season is here, and millions of Americans will click through benefits portals in the next few weeks without slowing down at the most expensive decision on the screen: which tax-advantaged health account to fund.
Two accounts dominate the choice, and they sound almost interchangeable.
One is an FSA, a flexible spending account.
The other is an HSA, a health savings account.
The difference between them can be worth thousands of dollars a year — or it can vanish entirely if you pick the one you're not eligible for.
Here's the part that trips people up: you can't simply choose an HSA because it sounds better.
If you're enrolled in a traditional copay plan or most PPOs, the HSA door is closed, and an FSA — usually a health care FSA or a limited-purpose version — is your only option.
If you are in a qualifying high-deductible health plan, the HSA wins on nearly every structural point.
Your contributions go in pre-tax, grow tax-free, and come out tax-free for qualified medical costs.
The account is yours, it rolls over year after year, and the money stays with you even if you change jobs.
Some people invest the balance and let it sit for decades.
The FSA works differently, and the trade-off is real.
You set aside money pre-tax, but in most cases you have to spend it within the plan year or a short grace period.
Miss the deadline and the leftover balance generally goes to your employer.
On the plus side, the full annual amount is available to you on day one, even before you've contributed all of it — useful if a big dental bill or surgery lands in January.
For 2025, the health care FSA contribution limit is $3,300 per employer, with a carryover of up to $660 if your plan offers it.
For HSAs in 2025, the limit is $4,300 for individual coverage and $8,550 for family coverage, plus a $1,000 catch-up contribution if you're 55 or older.
Those HSA figures adjust most years for inflation, so check the current numbers before you set your payroll deduction.
One more thing worth knowing: an HSA can function as a retirement account.
After age 65, you can withdraw funds for any purpose and pay only ordinary income tax, similar to a traditional IRA.
Before 65, non-medical withdrawals come with income tax plus a 20% penalty.
The practical move is boring but effective.
First, confirm which account your health plan actually allows — this is a plan-design question, not a preference.
Then estimate your real out-of-pocket costs for the coming year: prescriptions, copays, glasses, dental work, therapy, and any planned procedures.
If you're in an FSA, contribute close to that number, not the maximum, because unspent money is the one mistake you can't undo.
If you have an HSA, consider contributing as much as your budget allows and paying smaller medical bills out of pocket when you can, letting the balance compound.
That strategy only works if you have the cash flow to absorb those costs, so don't stretch yourself thin chasing a tax break.
The account you pick matters less than the number you put in it.
Before you hit submit, pull last year's receipts and your Explanation of Benefits statements.
Final Thoughts
That stack of paper is a better predictor of next year's costs than any benefits brochure — and it's the difference between using these accounts well and just checking a box.