If you have a flexible spending account through work, there's a deadline coming that most people miss entirely.
And the penalty for missing it is unusually harsh: you simply lose the money.
Not taxed, not rolled into a retirement account, not refunded.
Here's the part that rarely makes the headlines.
When you forfeit that cash, your employer generally gets to keep it.
Under IRS rules, companies can use leftover FSA funds to offset their own costs of running the plan.
So the "use it or lose it" rule isn't just a nudge to schedule that dentist appointment.
It's a quiet transfer of your wages back to your employer's books.
Most FSA deadlines land on December 31, but the exact rules depend on how your plan is set up.
Some employers offer a grace period, letting you spend last year's balance until March 15.
Others offer a carryover, letting you roll a limited amount forward.
The catch: you don't automatically get either one.
Your plan either has it or it doesn't, and it's spelled out in your benefits documents, not in a text from HR the week before New Year's.
The carryover amount is also smaller than most people assume.
Meanwhile, the amount you could set aside for 2025 rose to $3,300.
That gap between what you can sock away and what you're allowed to protect is where a lot of money quietly disappears.
And there's a timing trap that catches even careful savers.
If you swipe your FSA card on December 28, that charge still has to clear and post to the plan by the deadline.
A transaction that sits pending for a few days can fall on the wrong side of the cutoff.
The fix is boring but effective: spend earlier in the month, and keep the receipt.
What actually counts as eligible is broader than most people think, which is good news.
Over-the-counter medicine, bandages, sunscreen, feminine products, contact lens solution, and certain menstrual and pregnancy test products all qualify now.
So do glasses, prescription sunglasses, and many dental and vision costs.
You generally can't use FSA money for straight cosmetic procedures, gym memberships, or most vitamins, though a doctor's letter can occasionally change the math on some of these.
The real problem is that FSAs punish people who guess wrong about their own health.
A healthy year means money you can't get back.
It's a structure that shifts risk onto workers while handing the leftover to whoever administers the account, and it's worth asking your HR team directly where forfeited funds go in your specific plan.
Before the deadline, log into your FSA portal, look at the actual balance, and check whether your plan offers a grace period or carryover in writing.
Then spend on things you'll genuinely use, not on stuff you're buying just to avoid losing it.
Final Thoughts
If your employer is pocketing unspent balances while offering no carryover, that's a benefits question worth raising out loud.