Open enrollment season is here, and millions of Americans are about to make the same costly choice they make every year.
They'll pick a flexible spending account when a health savings account would have put real money in their pocket.
The difference between these two accounts is not small.
It can mean hundreds of dollars slipping away each year, often without you noticing until the money is already gone.
You decide during open enrollment how much to set aside, and that money typically vanishes if you don't spend it by the deadline.
A health savings account works the opposite way.
The funds roll over year after year, and you can invest them for retirement.
That single difference changes the math dramatically.
The catch is that HSAs come with strict rules.
You can only open one if you're enrolled in a high-deductible health plan.
That plan often means paying more out of pocket before coverage kicks in, which scares people off.
But the tax perks are unusually generous.
Contributions go in pre-tax, growth is tax-free, and withdrawals for qualified medical costs come out tax-free too.
It's one of the few accounts the IRS treats that kindly.
If your employer offers a limited-purpose FSA for dental and vision, or if you have predictable medical costs and no access to an HDHP, the account can work fine.
The trap is overestimating how much you'll spend.
The average FSA forfeiture runs into hundreds of dollars per person, and that money simply stays with your employer.
If you go the FSA route, aim low on your estimate, then use the funds for glasses, contacts, prescriptions, or eligible over-the-counter items before the deadline.
If you have an HDHP option and can cover the higher deductible, run the numbers on an HSA.
Many employers also contribute to HSAs, which is essentially free money.
And remember that HSA funds can be used for medical costs decades from now, so you're not racing a clock.
FSA deadlines sometimes allow a grace period or a small carryover, but the rules vary by employer and change year to year.
HSA contribution limits adjust annually, and once you hit 65, the rules loosen even further.
Contribution limits for 2025 are $4,300 for individual coverage and $8,550 for family coverage on the HSA side, with an extra $1,000 if you're 55 or older.
FSA limits sit at $3,300 for 2025, though employers can add a carryover.
The bottom line for most workers with an HDHP is simple.
An HSA is the stronger long-term play because the money is yours and it keeps growing.
An FSA is a spending tool, not a savings tool, and treating it like a savings account is how people lose money.
Read your plan documents carefully, ask HR which accounts you actually qualify for, and don't let a default option make the decision for you.
My take: most Americans leave free money on the table by defaulting to whatever box is pre-checked.
Spend twenty minutes comparing your options this enrollment season.
Final Thoughts
That small bit of homework could be worth more than most of the deals you'll chase all year.