A flexible spending account is worth it only if you will actually spend the money you set aside

A flexible spending account (FSA) lets you set aside pre-tax dollars for medical expenses, which means you pay less in federal income tax and Social Security tax on that money. But the account comes with a hard rule: money you don't spend by the end of the plan year is forfeited. That risk makes FSAs useful for some people and a trap for others.

The math works in your favor only if three things are true: you know roughly how much you'll spend on medical care this year, you can afford to lock that money away before you spend it, and you won't panic and withdraw it early. If any of those conditions fail, a regular taxable savings account or an HSA (which has no use-it-or-lose-it rule) is safer.

Key Takeaways

  • FSA contributions reduce your taxable income, so you save roughly 20 to 40 percent in federal and state taxes on the money you set aside, depending on your tax bracket.
  • Any money left in your FSA at the end of the plan year is forfeited—there is no rollover, no exception, and no way to get it back except through a limited carryover or grace period your employer may offer.
  • You must decide how much to contribute during open enrollment, and you cannot change that amount mid-year unless you have a may have access to life event like a birth, marriage, or loss of coverage.
  • FSAs work best for people with predictable medical expenses—regular prescriptions, ongoing therapy, dental work, or vision care—not for people who rarely see a doctor.
  • If you are unsure whether you will spend the money, an HSA is a safer choice because unused funds roll over year to year and grow tax-free.

How the tax savings work

When you contribute to an FSA, that money comes out of your paycheck before federal income tax, Social Security tax, and Medicare tax are calculated. If you contribute $2,500 to an FSA and your combined federal, state, and payroll tax rate is 30 percent, you save roughly $750 in taxes on that contribution.

The actual savings depend on your tax bracket and your state. Someone in the 22 percent federal bracket who also pays state income tax and payroll taxes might save 30 to 35 percent. Someone in the 12 percent federal bracket might save 20 to 25 percent. The higher your tax bracket, the more you save.

That tax savings is real money—it happens automatically, and you don't have to do anything to claim it. But it only matters if you actually spend the money in the account. If you contribute $2,500 and spend only $1,200, you lose the tax savings on the $1,300 you didn't use.

The use-it-or-lose-it rule and what happens to leftover money

At the end of your plan year (usually December 31), any balance remaining in your FSA is forfeited. Your employer keeps it. There is no exception for emergencies, no rollover to next year, and no way to withdraw it without penalty. This rule exists because of IRS regulations that prevent FSAs from becoming general savings accounts.

Some employers offer a grace period of up to 2.5 months into the next year, which lets you spend down your FSA balance on medical expenses incurred during that grace period. A smaller number of employers allow a carryover of up to $610 (as of 2024, adjusted yearly for inflation) into the next plan year. Ask your benefits administrator whether your plan offers either option—it changes the calculation significantly.

If your employer offers neither grace period nor carryover, you must be conservative with your contribution. Overestimate slightly, and you lose money. Underestimate, and you miss the tax savings on expenses you could have covered.

When an FSA makes financial sense

An FSA is worth using if you have predictable medical expenses you know you will incur. Examples include monthly prescriptions, regular therapy or counseling sessions, ongoing dental work, vision care (glasses, contacts, exams), or physical therapy. If you can reasonably estimate your spending within a few hundred dollars, an FSA reduces your tax burden.

FSAs also cover expenses many people don't realize are may be able to access: over-the-counter medications (allergy medicine, pain relievers, cold medicine), first-aid supplies, feminine hygiene products, sunscreen, and certain medical equipment like crutches or heating pads. If you buy these items regularly, they add up and make an FSA contribution safer.

The account also works well if you are having a planned medical procedure—surgery, dental work, or a course of treatment—during the plan year. You can estimate the out-of-pocket cost and set aside that amount, knowing you will spend it.

When an FSA is risky or not worth it

An FSA is a poor choice if your medical spending is unpredictable or low. If you rarely see a doctor, don't take regular medications, and have good health, you might spend only $500 to $1,000 a year on medical care. Contributing $2,500 to an FSA means losing $1,500 or more at year-end.

FSAs are also risky if you might need the money for something other than medical expenses. The account is locked—you cannot withdraw funds for any other reason without paying income tax plus a 20 percent penalty on the withdrawal. If you contribute $2,500 and face a financial emergency, you cannot touch that money without a steep cost.

People who change jobs mid-year should be cautious. If you leave your employer, you typically lose access to the FSA, though you may be able to continue it through COBRA (at full cost) or use it through the end of the plan year depending on your employer's rules. Unused money is still forfeited.

FSA versus HSA: which is better for you

An HSA (Health Savings Account) is available only if you have a high-deductible health plan. Unlike an FSA, an HSA has no use-it-or-lose-it rule—unused money rolls over year to year and can grow indefinitely. You also get the same tax break on contributions, and you can invest the money to grow it further.

If you have access to both an FSA and an HSA through your employer, the HSA is almost always the better choice because of the rollover feature. You can contribute to the HSA, spend what you need, and keep the rest for future years or retirement. An FSA is only better if your employer offers a generous match (rare) or if you have very predictable medical expenses and your employer offers a carryover or grace period.

If you have access to only an FSA, use it only if you are confident you will spend most or all of the money. Otherwise, save the money in a regular taxable account and skip the FSA.

How to decide on a contribution amount

Start by looking at your medical spending from the past two years. Add up what you spent on prescriptions, copays, deductibles, dental work, vision care, therapy, and any medical equipment or supplies. Divide by two to get an average year.

Then add any planned medical expenses for the coming year—a scheduled surgery, dental work, or a course of treatment. That total is your baseline.

If your employer offers a grace period or carryover, you can contribute slightly above that baseline because you have a buffer. If not, stay at or slightly below your baseline. The IRS limit for 2024 is $3,300 per year (adjusted yearly for inflation), but most people should contribute far less.

If you are unsure, contribute less rather than more. A smaller contribution you fully spend is better than a larger one where you forfeit the remainder.

Frequently Asked Questions

Can I change my FSA contribution mid-year?

Only if you have a may have access to life event: birth or adoption of a child, marriage or divorce, loss of health coverage, a significant change in medical expenses, or a change in your spouse's benefits. Job changes and raises do not may have access to. You must request the change within 30 to 60 days of the event, depending on your employer's rules.

What happens to my FSA money if I leave my job?

You lose access to the account immediately in most cases. Money you have not yet spent is forfeited. Some employers allow you to continue the FSA through COBRA, but you pay the full premium yourself. Check with your benefits administrator before you leave whether continuation is an option.

Can I use my FSA for my spouse or children?

Yes, you can use FSA money for medical expenses of your spouse and dependents, even if they are not on your health insurance plan. The expense must be may be able to access and you must have receipts. You cannot use it for their insurance premiums unless they are COBRA premiums.

What counts as a medical expense in an FSA?

may be able to access expenses include copays, deductibles, prescriptions, dental work, vision care, therapy, medical equipment, and many over-the-counter items like pain relievers and allergy medicine. Health insurance premiums, cosmetic procedures, and gym memberships do not count. Your employer should provide a full list, or check IRS Publication 502 for details.

Is there any way to get my money back if I don't spend it?

No. Once the plan year ends, forfeited money is gone. The only exception is if your employer offers a grace period (usually 2.5 months) or a carryover (up to $610 as of 2024). Ask your benefits administrator whether your plan has either option before you contribute.