Open enrollment season is here, and millions of Americans are staring at a benefits form with two acronyms that look almost identical: FSA and HSA.
Pick the wrong one and you could leave real money on the table — or lose cash you already set aside.
The difference comes down to who controls the account, when you can use it, and what happens if you don't.
A flexible spending account, or FSA, is the one your employer usually owns.
You decide how much to contribute during open enrollment, and that money comes out of your paycheck before taxes.
The catch: it's generally use-it-or-lose-it.
If you don't spend the balance by the deadline, most of it vanishes.
Some employers offer a grace period or let you roll over a small amount, but the ceiling is low.
A health savings account, or HSA, works differently.
You can only open one if you're enrolled in a high-deductible health plan.
In exchange, the account is yours — it follows you when you change jobs, and the balance rolls over year after year with no deadline.
Many employers also chip in a contribution, which is essentially free money.
The tax treatment is where the HSA pulls ahead.
Contributions go in pre-tax, growth is tax-free, and withdrawals for qualified medical costs come out tax-free.
After age 65, you can even withdraw for non-medical expenses and pay ordinary income tax, similar to a traditional IRA.
It can cover things an HSA can't always reach, and it's available to people who don't qualify for an HSA.
If you know you'll have predictable costs — glasses, dental work, a recurring prescription — an FSA lets you pay for them with untaxed dollars.
Financial advisors often suggest estimating only the expenses you're confident about, because unused money is gone.
With an HSA, the risk of saving "too much" basically doesn't exist.
You can invest the balance and let it grow for retirement medical costs, which are one of the biggest expenses many households face later in life.
One more wrinkle: you can't contribute to an HSA if you're covered by most general-purpose FSAs, including a spouse's.
That rule trips up plenty of couples who each sign up for separate accounts without checking.
A limited-purpose FSA for dental and vision, paired with an HSA, is allowed.
If you're choosing between them, the HSA usually wins for anyone eligible, especially if you can afford to pay current medical bills out of pocket and let the account compound.
The FSA makes sense when you don't have an HSA-eligible plan or you have a stack of known expenses coming.
Before you check a box, look at your plan's deductible, your employer's match, and last year's actual spending.
A ten-minute review can be worth several hundred dollars.
The bottom line: HSAs reward patience and long-term thinking, while FSAs reward accurate guessing.
Final Thoughts
Most people underestimate how fast an FSA balance can expire, so when in doubt, contribute less than you think you'll spend.