If your employer offers a flexible spending account and you’re not using it, you could be leaving hundreds — even thousands — of dollars in tax savings on the table. What is an FSA, exactly? It’s a pre-tax savings account that lets you set aside money from your paycheck to pay for qualified medical expenses, effectively giving you a discount on healthcare equal to your marginal tax rate. The catch: most FSA funds must be used within the plan year or you forfeit them. This guide explains how FSAs work, what they cover, and how to use yours wisely. For more on healthcare benefits and policy, explore our healthcare policy guide.
How a Flexible Spending Account Works
An FSA is an employer-sponsored benefit that allows you to contribute pre-tax dollars to pay for eligible out-of-pocket healthcare costs. During your employer’s open enrollment period, you elect an annual contribution amount. That money is deducted from your paychecks in equal installments throughout the year — before federal income tax, Social Security tax (FICA), and state income tax are calculated.
Here’s what makes FSAs unusual: your full annual election is available on day one of the plan year, even though you haven’t contributed all of it yet. If you elect $2,500 and have a $2,000 medical expense in January, you can use the FSA to cover it immediately — even though only one month’s worth of deductions has occurred. Your employer fronts the difference. This “uniform coverage rule” is a significant advantage over HSAs, where you can only spend what you’ve actually deposited.
The primary types include a healthcare FSA (the most common, covering medical, dental, and vision expenses), a dependent care FSA (for childcare and elder care expenses, with separate rules and limits), and a limited-purpose FSA (restricted to dental and vision, designed to be paired with an HSA). This article focuses on healthcare FSAs.
FSA Contribution Limits and Tax Savings
For 2025, the IRS sets the maximum healthcare FSA contribution at $3,300 per employee. If both spouses have access to FSAs through their respective employers, each can contribute up to the maximum — potentially sheltering $6,600 from taxes for a household. Employers may set lower limits, so check your plan documents.
The tax savings are straightforward and meaningful. Contributions avoid federal income tax, Social Security tax (7.65% for most employees), and state income tax. For someone in the 22% federal bracket living in a state with 5% income tax, every $1,000 contributed to an FSA saves approximately $347 in taxes. On a full $3,300 contribution, that’s over $1,140 in annual tax savings — money that would otherwise go to the government.
Unlike HSA contributions, FSA contributions cannot be deducted on your tax return if made outside of payroll. FSAs are exclusively employer-facilitated. Self-employed individuals and those whose employers don’t offer FSAs cannot participate. According to the IRS, the contribution limit is adjusted annually for inflation.
What Can You Spend FSA Money On?
The list of FSA-eligible expenses is extensive and was expanded by the CARES Act of 2020. Qualified expenses include doctor copays and coinsurance, prescription medications, over-the-counter drugs (including pain relievers, allergy medications, and cold remedies), dental care (cleanings, fillings, crowns, dentures, orthodontics), vision care (eye exams, prescription glasses, contact lenses, lens solution), mental health services, and physical therapy.
Since the CARES Act, menstrual products (pads, tampons, cups), sunscreen, first aid supplies, and over-the-counter medications without a prescription are all eligible. Medical equipment such as blood pressure monitors, thermometers, crutches, and CPAP supplies qualifies. Some less obvious eligible expenses include acupuncture, chiropractic care, hearing aids, fertility treatments, and smoking cessation programs.
Expenses that are generally not eligible include cosmetic procedures, gym memberships (unless prescribed by a doctor for a specific condition), vitamins and supplements (unless prescribed), toiletries, and health insurance premiums. The IRS Publication 502 provides the definitive list. When in doubt, your FSA administrator’s website usually has a searchable eligibility tool. Understanding your insurance deductible can help you estimate how much to set aside in your FSA for the year.
The “Use It or Lose It” Rule — and Exceptions
The biggest drawback of FSAs is the forfeiture rule: unused funds at the end of the plan year are lost. This is fundamentally different from HSAs, where balances roll over indefinitely. However, employers may offer one of two relief provisions (but not both):
- Grace period: An additional 2.5 months after the plan year ends to use remaining funds. If your plan year runs January through December, you’d have until March 15 of the following year to incur expenses.
- Carryover: The ability to roll over up to $660 (2025 limit) of unused funds into the next plan year. This amount adjusts annually for inflation.
Not all employers offer either provision, and many employees don’t realize which option their plan includes. Check your plan documents during open enrollment. The forfeiture rule means careful planning is essential — contribute too much and you lose the excess; contribute too little and you miss out on tax savings. Review your prior year’s medical expenses as a baseline for your election.
Smart Strategies for Using Your FSA
Start by estimating your annual out-of-pocket medical expenses. Review the past year’s costs: copays, prescriptions, dental work, glasses, and any planned procedures. Add a buffer for unexpected needs, but be conservative — it’s better to underestimate slightly than to lose money at year-end.
Schedule routine appointments strategically. If you have remaining FSA funds in the fourth quarter, schedule dental cleanings, eye exams, or annual physicals before the deadline. Stock up on eligible over-the-counter items — contact lens solution, first aid supplies, sunscreen, and OTC medications. Many FSA-eligible online stores (like the FSA Store) make last-minute spending easy.
Consider timing larger expenses. If you need new glasses, dental work, or orthodontics, plan these for a year when your FSA can offset the cost. For families, coordinate with your spouse’s FSA or benefits to maximize coverage. Keep all receipts — your FSA administrator may request documentation for any reimbursement claim, and the IRS can audit FSA usage.
FSA vs HSA: Key Differences
Both accounts save you money on healthcare through tax advantages, but they work quite differently. The most critical distinction: FSA funds generally expire at year-end, while HSA funds last forever. HSAs require a high-deductible health plan; FSAs work with any employer health plan. HSAs are individually owned and portable; FSAs are tied to your employer and typically forfeited when you leave (you can submit claims for expenses incurred before departure, but the account itself doesn’t follow you).
HSAs offer investment options for long-term growth; FSAs do not. However, FSAs have the advantage of full-year availability from day one — your entire election is accessible immediately, while HSA spending is limited to your current balance. For a detailed side-by-side comparison, see our HSA vs FSA guide.
Frequently Asked Questions
Can I change my FSA contribution mid-year?
Generally, no. FSA elections are locked in for the plan year once open enrollment closes. However, qualifying life events — such as marriage, divorce, birth or adoption of a child, a spouse gaining or losing coverage, or a change in employment status — may allow a mid-year adjustment. Check with your HR department about what qualifies under your specific plan.
What happens to my FSA if I leave my job?
Typically, your FSA ends on your last day of employment (or the end of the month, depending on the plan). You can submit claims for eligible expenses incurred before your termination date, but you lose access to any remaining balance. Some employers offer COBRA continuation for FSAs, but it’s rarely cost-effective since you’d pay the full contribution plus a 2% admin fee without the pre-tax benefit.
Can I have both an FSA and an HSA?
Not a general-purpose healthcare FSA and an HSA simultaneously. However, you can pair an HSA with a limited-purpose FSA (covering only dental and vision) or a post-deductible FSA. If you’re deciding between the two, your health plan type usually determines which is available — HDHPs pair with HSAs, while traditional plans pair with FSAs.
Are FSA contributions subject to Social Security tax?
No. FSA contributions are excluded from FICA (Social Security and Medicare) taxes, which means you save an additional 7.65% beyond your income tax rate. This is an advantage that HSAs share when contributions are made through payroll, but it’s often overlooked when calculating the true value of an FSA.
The Bottom Line
A flexible spending account is one of the simplest ways to reduce your healthcare costs — if you use it strategically. The pre-tax contributions effectively give you a discount on every dollar spent on eligible medical expenses, from prescriptions and copays to dental work and glasses. The key is careful planning: estimate your annual expenses conservatively, know your plan’s grace period or carryover provisions, and schedule routine care to maximize your benefit. Even a modest FSA contribution of $1,000 to $1,500 can save you $300 to $500 in taxes annually — money that stays in your pocket instead of going to the IRS.