If you still have money in a flexible spending account, the clock is ticking.

Last year during open enrollment, you may have elected to fund an FSA with pre-tax dollars that you can spend on eligible medical expenses, such as doctor's visit copays, dental procedure fees or prescription drugs.

Generally speaking, you have until the end of the year to spend the money in your account or you lose it. That means if you had fewer medical expenses this year than you thought, you may be sitting on a pile of cash that will disappear if you don't figure out a way to spend it.

Don't panic. If you're strategic, you still have time to spend your FSA money in a timely manner and on things that you'll be happy to buy. 

But avoid these three common mistakes that tend to trip people up near the deadline.

1. You think you're running out of time to spend your FSA money

The Dec. 31st deadline may be fast approaching, but depending on your company's specific policy, you may have more time than you think.

Ask your HR department or the FSA administrator at your company to get clarification on when your FSA funds expire, says Rachel Rouleau, chief compliance officer at FSAStore.com.

"The most common plan year is January to December," says Rouleau. "But it could end it on any month throughout the year, depending on when your employer has made that plan year for your benefits. So you want to know when [your deadline] is."

Ask about extensions, too. "You could also have a two-and-a-half month grace period at the end of your plan year to continue to spend down funds," Rouleau says. That means if you have a Dec. 31 deadline, you may be able to use 2024 funds on expenses through March 15.

And even if you do have a hard and fast deadline, you may be able to carry some or all of your remaining FSA balance over into next year's plan.

However, your employer can either offer a two-and-a-half month grace period or a carryover option, but not both, according to the IRS, so be sure to ask.

2. You haven't spent your FSA dollars on health tech yet

With advances in wearable technology that can help you treat or prevent illness, the number of items you can spend your FSA money on is expanding. Online stores such as FSAStore.com and Amazon's FSA Store feature devices such as blood pressure monitors and digital scales that fall under the IRS's definition of a health-care expense.

But make sure to double check with your FSA administrator that certain items are eligible before purchasing. Your administrator may require a letter of medical necessity from your doctor that proves you need the item to treat a specific health condition, Rouleau says.

"The big unlock is the letter of medical necessity," says Nery Solano, head of consumer marketing at TrueMed, an online marketplace specializing in FSA-eligible items that need medical signoff before purchase.

The site connects users with licensed practitioners in TrueMed's network who can write letters of medical necessity for items such as exercise bikes, supplements and cold plunge pools. You may also request a letter of medical necessity from your primary care physician, if you have one.

3. You don't use your FSA for over-the-counter medications and menstrual products

In years past, deadline FSA spending meant either booking last-minute appointments with specialists, splurging on prescription sunglasses or scrounging around the drugstore for medical products such as ace bandages and knee braces.

Thanks to the 2020 CARES Act, you can use your FSA funds to purchase virtually any over-the-counter medication, as well as menstrual products such as tampons, pads and liners.

But remember, you may have to document what you've bought in order to be reimbursed by your FSA plan administrator. Rouleau strongly recommends keeping your receipts for all purchases, even if your plan does not require documentation up front. 

"You should always keep your receipts, no matter what," she says.

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