Open enrollment season has a way of making otherwise smart people freeze up in front of a benefits portal.
One of the most common stumbles is choosing between an FSA and an HSA, two accounts that sound almost identical and behave very differently.
The letters matter more than the paperwork suggests.
An FSA, or flexible spending account, is a use-it-or-lose-it pot of pretax money your employer sets up.
An HSA, or health savings account, is a bank account you own, and it only comes with a high-deductible health plan.
That single ownership difference drives everything else.
With a traditional FSA, you generally have to spend the balance by the end of the plan year, though many employers offer a grace period or let you roll over a limited amount.
Miss that window and the leftover cash can vanish.
Employees forfeited an estimated $400 million to $500 million in FSA funds in a single recent year, according to one widely cited analysis.
The money rolls over year after year, earns interest, and can be invested once your balance climbs past a set threshold.
You keep it even if you change jobs or retire.
In 2025, you can contribute up to $4,300 for individual coverage and $8,550 for family coverage, plus an extra $1,000 if you're 55 or older.
You can't just sign up for an HSA because it sounds better.
Your health plan has to qualify as high-deductible, which means a minimum deductible of $1,650 for self-only coverage in 2025 and $3,300 for family coverage.
If your employer only offers a traditional PPO, an HSA isn't on the menu.
There's also a quiet trap for anyone on Social Security.
Once you enroll in Medicare, you can no longer contribute to an HSA, though you can still spend what's already there.
Contributing after you're enrolled can trigger tax headaches, so timing your last contribution matters.
Both accounts share one big perk: you skip federal income tax on the money going in, and withdrawals for qualified medical costs come out tax-free.
You can use them for copays, prescriptions, glasses, contact lenses, dental work, and a long list of other expenses.
The IRS publishes the full list in Publication 502, and it's worth a look before you guess.
Which one wins depends on your situation.
If you're healthy, want to build a long-term medical nest egg, and can handle a higher deductible, the HSA is hard to beat.
If you have predictable, ongoing medical costs and your employer offers a generous FSA match, the FSA can still make sense.
A few practical moves before you decide: estimate your real out-of-pocket costs for the year, check whether your FSA has a grace period or rollover, and confirm your plan actually qualifies for an HSA.
If you're married, remember you can each open your own HSA, but family coverage limits still apply.
The bottom line: these accounts aren't interchangeable, and picking the wrong one can mean losing money you already set aside.
Final Thoughts
A little homework now beats a forfeited balance in December.