Open enrollment paperwork can feel overwhelming, especially when it’s packed with acronyms. If you’ve found yourself asking “what is a FSA?” you’re in the right place. A flexible spending account is an employer-sponsored benefit that lets you set aside pre-tax money from your paycheck to pay for qualified medical, dental, and vision expenses. It’s one of the simplest ways to save on healthcare costs you’re already paying.
Roughly 44% of employers with 500 or more employees offer FSAs, according to benefits industry surveys. Understanding how they work, what they cover, and how to avoid common pitfalls puts you in a position to take full advantage of this tax benefit.
How a Flexible Spending Account Works
During your employer’s open enrollment period, you choose how much to contribute to your FSA for the upcoming plan year. The maximum for 2025 is $3,300, as set by the IRS. That amount is divided evenly across your paychecks and deducted before federal income tax, state income tax, and FICA payroll taxes are calculated.
Here’s what makes an FSA particularly useful: your full annual election is available from day one. If you elect $3,300 and need $2,500 in dental work in January, you can use your FSA to cover it immediately, even though only a fraction of your contributions have been deducted at that point. Your employer fronts the difference and recovers it through your remaining payroll deductions.
You typically access the funds through an FSA debit card tied to your account. When you swipe it at a pharmacy, doctor’s office, or eligible retailer, the purchase is deducted from your FSA balance. You can also pay out of pocket and submit receipts for reimbursement through your plan administrator’s website or app.
Types of FSAs
There are three main types, and each serves a different purpose. The health care FSA is the most common, covering medical, dental, and vision expenses for you, your spouse, and your dependents. This is what most people mean when they ask “what is a FSA?”
The dependent care FSA covers eligible childcare and elder care expenses. It has a separate contribution limit of $5,000 per household ($2,500 if married filing separately) and different rules around fund availability. Unlike the health care FSA, dependent care funds are only available as contributions accumulate rather than being front-loaded.
The limited-purpose FSA covers only dental and vision expenses. It exists primarily for people enrolled in a high-deductible health plan who also have a health savings account, since a general-purpose FSA would disqualify them from HSA contributions. For a comparison of FSAs and HSAs, see our HSA vs FSA guide.
What Can You Buy With an FSA?
The IRS defines eligible expenses in Publication 502, and the list is broader than most people realize. Standard medical expenses like copays, deductibles, prescription drugs, dental fillings, and eye exams all qualify. But so do over-the-counter medications (since the CARES Act of 2020), menstrual care products, sunscreen, first-aid supplies, hearing aids, crutches, and even mileage to medical appointments.
Items that don’t qualify include health insurance premiums, cosmetic procedures, gym memberships, general wellness supplements, and any product that doesn’t treat a specific medical condition. For the complete breakdown, visit our FSA eligible items guide.
The Use-It-or-Lose-It Rule
This is the most important rule to understand. Any money left in your FSA at the end of the plan year is forfeited unless your employer offers one of two IRS-approved provisions. The first is a grace period of up to 2.5 additional months to spend remaining funds. The second is a carryover of up to $660 (2025 limit) into the next plan year.
Your employer can offer one of these options or neither, but not both. Check your plan documents to see which applies. If your plan has no grace period or carryover, every dollar you contribute must be spent on eligible expenses within the plan year or it’s gone.
This rule is why accurate planning matters. Contributing more than you’ll spend means losing money. Contributing too little means missing tax savings. Aim to contribute an amount equal to your predictable, recurring medical expenses, then add a buffer for likely incidental purchases like OTC medications and first-aid supplies.
Tax Savings: The Real Value
The financial benefit of an FSA comes entirely from the tax treatment. Every dollar you contribute avoids federal income tax, state income tax (in most states), and FICA taxes (Social Security and Medicare at 7.65%). For an employee earning $60,000 in the 22% federal bracket with a 5% state tax rate, contributing the full $3,300 saves approximately $1,143 in taxes. That’s a guaranteed return you won’t find in any investment account.
Put differently, you’re paying for medical expenses at a 35% discount compared to using after-tax dollars. Prescriptions, copays, and dental work cost the same amount either way, but paying with pre-tax FSA dollars means you keep more of your earnings. This is why understanding what is a FSA matters for anyone with predictable healthcare costs.
How to Enroll
FSA enrollment happens during your employer’s open enrollment period, typically held in the fall for a plan year starting January 1. New hires can usually enroll within 30 to 60 days of their start date. You choose your annual contribution amount at enrollment, and in most cases, you cannot change it mid-year unless you experience a qualifying life event.
Qualifying life events include marriage, divorce, birth or adoption of a child, death of a spouse or dependent, and gaining or losing coverage under another plan. If one of these occurs, you generally have 30 days to request a contribution change. Outside of these events, your election is fixed for the plan year.
Common FSA Mistakes to Avoid
Overcontributing is the most expensive mistake. If you contribute $3,300 but only spend $2,000 on eligible expenses, you forfeit the remaining $1,300 (minus any carryover amount). Start with your known recurring costs and add cautiously.
Failing to submit claims before the deadline is another common error. Most plans allow you to submit claims for expenses incurred during the plan year for a period after the year ends (called the run-out period, typically 90 days). Missing this window means losing reimbursement on money you’ve already spent.
Not keeping receipts creates problems during audits. Your FSA administrator may request documentation for any purchase, and if you can’t provide it, the expense may be denied and treated as taxable income. Save every receipt, or use your administrator’s mobile app to photograph and upload them immediately.
Frequently Asked Questions
Can I use my FSA for my family’s expenses?
Yes. Your health care FSA covers qualified medical expenses for you, your spouse, and your tax dependents, even if they’re not enrolled in your employer’s health plan. This makes FSAs valuable for families with healthcare costs spread across multiple family members.
What happens to my FSA if I get laid off or quit?
Your FSA access typically ends on your last day of employment or at the end of the month you leave, depending on your plan. You can submit claims for expenses incurred before that date during the run-out period. You may be offered COBRA continuation for your FSA, but it’s rarely cost-effective since you’d pay the full contribution without the pre-tax benefit.
Can I have an FSA without health insurance?
Generally, no. Health care FSAs are offered in conjunction with an employer-sponsored health plan. You must be eligible for your employer’s health benefits to enroll in the FSA, though you may not be required to enroll in the health plan itself. Rules vary by employer.
How is an FSA different from an HRA?
A health reimbursement arrangement (HRA) is funded entirely by your employer, while an FSA is funded by your own pre-tax payroll deductions (sometimes with an employer match). HRAs are designed and controlled by the employer, with varying rules about portability and eligible expenses. FSAs give you more control over the contribution amount within IRS limits.
Make Your FSA Work for You
Now that you understand what a FSA is, the next step is deciding whether to enroll and how much to contribute. Review your household’s medical expenses from the past year, estimate upcoming costs, and contribute an amount you’re confident you’ll spend. The tax savings are automatic and immediate, and with the 2025 limit at $3,300, even a partial contribution can save you hundreds of dollars. For more on managing healthcare expenses and understanding your options, visit our healthcare costs guide and explore the current FSA contribution limits.