Open enrollment season is here, and millions of Americans are staring at two nearly identical-looking letters in their benefits portal: FSA and HSA.
Pick the wrong one, and you could forfeit hundreds of dollars or miss out on decades of tax-free growth.
Both accounts let you pay for doctor visits, prescriptions, and dental work with pre-tax dollars.
The difference is who controls the money and what happens when the calendar flips to January.
An FSA, or flexible spending account, is your employer's account.
You decide how much to set aside each year, and the IRS caps that at $3,200 for 2025.
The catch: most of it is use-it-or-lose-it.
Some employers offer a grace period or let you roll over up to $640, but plenty don't.
Spend too little, and that money simply vanishes.
Your full annual election is available on day one.
Pledge $3,000, and you can spend all $3,000 in February even though you've only contributed a few hundred dollars.
If you have a big planned procedure, that front-loaded access is real.
An HSA, or health savings account, works only if you're enrolled in a high-deductible health plan.
For 2025, that means a deductible of at least $1,650 for individuals or $3,300 for families.
The contribution limits are higher, too: $4,300 for individuals and $8,550 for families, plus an extra $1,000 if you're 55 or older.
You can invest it in index funds, and it grows tax-free.
Withdrawals for qualified medical expenses are also tax-free.
That's a triple tax advantage no other account in the tax code offers.
Here's the part that surprises people: you can reimburse yourself years later.
Keep receipts for a $200 dental bill from 2026, let the HSA compound for 20 years, and pull that $200 out tax-free whenever you want.
Financial planners call this a stealth retirement account.
You can also open an HSA outside your job and contribute on your own, as long as you're covered by a qualifying high-deductible plan.
That matters if you switch employers or freelance.
If your employer offers both, you generally can't use an FSA and an HSA together unless it's a limited-purpose FSA for dental and vision.
An HSA invested at a 7% average annual return over 30 years can turn $4,000 a year into roughly $400,000.
An FSA that resets every January can't do that.
That said, an FSA can still make sense if you have predictable, high medical costs and your employer doesn't offer a high-deductible plan.
Estimate your known expenses, then round down, not up.
Watch the fine print on dependent care FSAs, too.
Those are separate accounts with a $5,000 household limit, and they're still strictly use-it-or-lose-it.
The takeaway is simple: treat the HSA as a long-term wealth tool, not a debit card for copays.
Final Thoughts
Pay small bills out of pocket when you can, invest the balance, and let time do the work.