How a Flexible Spending Account Actually Works

A Flexible Spending Account (FSA) is a way to set aside pre-tax money from your paycheck to pay for medical and dependent care costs. You decide how much to contribute each year during your employer's open enrollment period, your employer deducts that amount from your paychecks before taxes are calculated, and you then use that money to pay for covered expenses. The money comes out of your paycheck automatically, so you never see it as taxable income.

The basic flow is straightforward: you contribute, the money sits in your account, you submit receipts or use a debit card to withdraw it for covered expenses, and whatever you don't use by the end of the plan year is forfeited. That last part—the "use it or lose it" rule—is the most important thing to understand about how FSAs differ from regular savings accounts.

Key Takeaways

  • You choose how much to contribute each year during open enrollment, and that amount is deducted from your paychecks before taxes are taken out.
  • You can only change your contribution amount during open enrollment or if you have a may have access to life event, such as a birth, marriage, or loss of other coverage.
  • Money you don't use by the end of the plan year is forfeited; most plans do not allow you to carry unused funds into the next year.
  • You pay for covered expenses out of pocket and then either submit receipts for reimbursement or use an FSA debit card to pay directly at the point of service.
  • Covered expenses include copays, coinsurance, deductibles, prescription medications, and certain dependent care costs, but not health insurance premiums or over-the-counter items without a prescription.

How Money Goes In: Payroll Deduction and Timing

Your FSA contribution happens through payroll deduction. During your employer's open enrollment period—usually once a year in the fall or early winter—you decide how much money to set aside for the coming plan year. That amount is divided equally across all your remaining paychecks for that year. If you contribute $2,400 for the year and receive 24 paychecks, $100 comes out of each paycheck before federal income tax, Social Security tax, and Medicare tax are calculated.

Because the money is deducted before taxes, you save money on taxes. If you are in the 22 percent federal tax bracket plus 7.65 percent for Social Security and Medicare, a $2,400 FSA contribution saves you roughly $720 in taxes. That is the main financial advantage of an FSA over simply setting aside money in a regular savings account.

You can only change your contribution amount during open enrollment or if you experience a may have access to life event: marriage, divorce, birth or adoption of a child, loss of other health coverage, or a significant change in your dependent care costs. Outside of these events, you are locked into your contribution for the entire plan year.

How Money Comes Out: Reimbursement and Debit Cards

Once money is in your FSA, you access it in one of two ways. The first is reimbursement: you pay for a covered expense out of pocket, keep the receipt, and submit it to your FSA administrator (usually a third-party company hired by your employer) along with a reimbursement request. The administrator reviews the receipt, confirms the expense is covered, and sends you a check or direct deposit within a few days to a week.

The second method is an FSA debit card. Your FSA administrator issues you a card that draws directly from your FSA balance. You use it like a regular debit card at pharmacies, doctors' offices, and other providers. Some cards require you to submit a receipt afterward to confirm the purchase was for a covered expense; others do not. The debit card is faster than reimbursement, but you need to keep receipts either way in case the administrator asks for proof later.

Not all employers offer both methods. Some provide only reimbursement; others provide only a debit card. Check with your benefits administrator to see what your plan offers. If you use the debit card, be aware that some merchants—particularly online retailers and certain pharmacies—may decline it because FSA cards have restrictions built in to prevent misuse.

What Counts as a Covered Expense

FSA funds can pay for a wide range of medical and dependent care costs. Medical expenses include copays, coinsurance, deductibles, prescription medications, dental work, vision care, mental health treatment, and medical equipment like crutches or blood pressure monitors. Dependent care expenses include daycare, preschool, and after-school care for children under age 13, as well as adult day care for a spouse or parent you claim as a dependent.

Over-the-counter medications and supplies are generally not covered unless you have a prescription from a doctor. Aspirin, cold medicine, and antacids purchased without a prescription do not count. However, items like bandages, first-aid supplies, and certain medical devices may be covered even without a prescription—the rules vary by plan and by product category.

Health insurance premiums, cosmetic procedures, and gym memberships do not count as covered expenses. Neither do most over-the-counter health products like vitamins or sunscreen, even if they have health benefits. If you are unsure whether a specific expense is covered, ask your FSA administrator before you pay for it. They can give you a definitive answer based on your plan's rules.

The Use-It-or-Lose-It Rule and Carryover Options

The defining feature of an FSA is the use-it-or-lose-it rule: any money you do not use by the end of the plan year is forfeited. You cannot roll it over to the next year, and you cannot withdraw it as cash. This is why FSAs require careful planning. If you contribute $2,400 and only use $1,800, the remaining $600 is gone.

Some employers offer a grace period of up to 2.5 months into the next plan year, during which you can still submit claims for expenses incurred in the previous year. This gives you a small window to catch expenses you forgot to claim. However, not all employers offer a grace period, and it does not extend the deadline indefinitely—it is still measured in weeks, not months.

A small number of employers also offer a carryover option that allows you to roll up to $610 (the amount changes annually) from one year into the next. This is rare and requires your employer to elect it. If your employer offers a carryover, you will see it clearly in your plan documents. Do not assume you have it unless you have confirmed it in writing.

How to Estimate Your Contribution

The hardest part of using an FSA is deciding how much to contribute. Contribute too little and you miss out on tax savings. Contribute too much and you forfeit money at year's end. The goal is to estimate your out-of-pocket medical and dependent care costs as accurately as possible.

Start by looking at your previous year's receipts and bills. How much did you spend on copays, deductibles, prescriptions, and dependent care? Add up those numbers. Then adjust for changes you expect in the coming year: a new medication, a change in your child care situation, or a planned procedure. Be conservative—it is better to contribute less and miss some tax savings than to contribute more and forfeit money.

The IRS sets an annual contribution limit for FSAs. For 2024, the limit is $3,300 for medical FSAs and $5,000 for dependent care FSAs. These limits change each year. Your employer will tell you the current limit during open enrollment. If you are married and both you and your spouse work, you can each open an FSA up to the limit, but your combined dependent care FSA contributions cannot exceed $5,000.

What Happens If You Leave Your Job

If you leave your job during the plan year, you generally forfeit any unused FSA balance. Some employers allow you to submit claims for expenses incurred before your departure date for a short period after you leave, but the money itself does not transfer to a new employer or to a personal account.

You may be able to continue your FSA coverage under COBRA (Consolidated Omnibus Budget Reconciliation Act), which allows you to keep your employer's health insurance for up to 18 months after you leave. However, COBRA coverage for an FSA is uncommon, and if it is available, you must elect it within 60 days of your departure. Check with your former employer's benefits administrator to see if COBRA FSA coverage is an option.

If you move to a new job with a different employer, you can open a new FSA with that employer during their open enrollment period or if you have a may have access to life event. The two accounts are separate; money from your old FSA does not carry over.

Frequently Asked Questions

Can I use my FSA for my spouse or children?

Yes, you can use FSA funds to pay for medical and dependent care expenses for your spouse and children, even if they are not covered under your health insurance plan. The expense must be a covered expense, and you must have receipts to prove it. Dependent care FSA funds can only be used for care of children under age 13 or a spouse or parent you claim as a dependent.

What if I submit a claim and it gets denied?

If your FSA administrator denies a claim, they must tell you why in writing. Common reasons include: the expense is not covered under your plan, the receipt does not show what was purchased, or the date of service is outside the plan year. You can appeal a denial by providing additional documentation or clarification. If the appeal is denied, the money stays in your account and you can use it for other covered expenses.

Can I get my FSA money back as cash if I do not use it?

No. FSA funds must be used for covered medical and dependent care expenses. You cannot withdraw the money as cash, and you cannot roll it over to the next year unless your employer offers a carryover option. Any unused balance at the end of the plan year is forfeited to your employer.

Do I need to submit receipts for every FSA debit card purchase?

It depends on your plan and your FSA administrator. Some require you to submit a receipt after every purchase; others only ask for receipts if the purchase seems questionable. Keep all receipts for at least three years in case your administrator asks for proof later. If you cannot provide a receipt when asked, the administrator may deny reimbursement or require you to repay the amount.

What if my plan year ends and I have money left over?

Any unused balance is forfeited at the end of the plan year. Some plans have a grace period of up to 2.5 months into the next year, during which you can still submit claims for expenses incurred in the previous year. Check your plan documents or ask your benefits administrator whether your plan has a grace period. If it does, you can use that time to submit any claims you missed before the deadline.