How a Medical Flexible Spending Account Works

A Medical FSA lets you set aside pre-tax money to pay for routine health care costs

A Medical Flexible Spending Account (FSA) is an employer-sponsored savings account where you contribute money before taxes are taken out of your paycheck. You then use that money to pay for medical expenses that your health insurance does not cover or covers only partially — things like copays, deductibles, prescription costs, and dental work. The tax savings come because the money you put in reduces your taxable income for the year.

The account is "flexible" because you choose how much to contribute each year (within IRS limits) and you decide which medical bills to pay from it. It is not the same as a Health Savings Account (HSA), which requires a high-deductible health plan and lets you carry money forward indefinitely. With a Medical FSA, you must spend the money within the plan year or lose it — though there are limited exceptions.

Medical FSAs are offered by many employers as part of their benefits package. You can only open one if your employer offers it; you cannot set one up on your own. The account is managed by a third-party administrator your employer chooses, and you typically access it through a debit card, online portal, or by submitting receipts for reimbursement.

Key Takeaways

• Medical FSA contributions come from your paycheck before income and payroll taxes are calculated, reducing your taxable income and your tax bill.
• You can use the account to pay for copays, deductibles, prescription medications, dental care, vision care, and other medical expenses not fully covered by insurance.
• The IRS sets an annual contribution limit (which changes yearly) and you must choose your contribution amount during your employer's open enrollment period.
• Money left unspent at the end of the plan year is forfeited, though your employer may offer a grace period or a limited carryover option.
• You need to submit receipts or documentation to prove expenses are medical in nature before the account administrator will reimburse you.

How contributions and tax savings work

When you enroll in a Medical FSA, you decide how much to contribute for the year and that amount is deducted from your paycheck in equal installments before federal income tax and Social Security tax are withheld. If you contribute $2,400 to an FSA and earn $50,000 annually, your taxable income drops to $47,600. This means you pay income tax and payroll tax only on the lower amount, which reduces your overall tax bill for the year.

The IRS sets a maximum contribution limit each year. For 2024, the limit is $3,200 per person per year (this limit changes annually, so check your plan documents for the current year). Your employer may set a lower limit, but cannot allow you to contribute more than the IRS maximum. If you are married and both you and your spouse work for employers that offer FSAs, you can each open your own account and each contribute up to the limit.

The tax savings depend on your tax bracket. If you are in the 22% federal tax bracket and contribute $2,400, you save roughly $528 in federal taxes alone. Add state and local taxes plus the 7.65% you would normally pay into Social Security and Medicare, and the total savings can reach 30% or more of your contribution.

What medical expenses you can pay for

The IRS maintains a detailed list of may be able to access medical expenses. Common ones include copays and coinsurance (the portion of a bill your insurance does not cover), deductibles, prescription medications, dental work, vision care including glasses and contact lenses, hearing aids, and mental health treatment. You can also use FSA funds for over-the-counter medications like pain relievers and allergy medicine, but only if you have a prescription or a letter from your doctor stating medical necessity.

Expenses that do not count include cosmetic procedures, gym memberships, vitamins (unless prescribed), and most over-the-counter items without a prescription. If you are unsure whether an expense is may be able to access, ask your plan administrator before you pay for it — they can tell you whether a specific item or service qualifies.

You do not have to use the money immediately. You can accumulate receipts throughout the year and submit them for reimbursement whenever you want, as long as the expenses occurred during the plan year. Some people pay for medical costs out of pocket and then reimburse themselves from the FSA later, which gives them flexibility in timing.

The use-it-or-lose-it rule and exceptions

Money left in your Medical FSA at the end of the plan year is forfeited — you cannot carry it forward to the next year. This is the biggest drawback of FSAs compared to HSAs. If you contribute $2,400 and spend only $1,800, the remaining $600 is lost. This rule exists because of IRS regulations designed to prevent people from using FSAs as long-term savings vehicles.

However, your employer may offer one or both of these options to soften the impact. A grace period allows you to spend money from the previous year's account during the first 2.5 months of the new plan year. So if your plan year ends December 31, you could use 2024 money through March 15, 2025. A carryover allows you to carry forward up to $640 (for 2024; this amount changes yearly) into the next year. Not all employers offer these, and you cannot have both a grace period and a carryover in the same plan — your employer chooses one or neither.

To avoid losing money, estimate your medical expenses carefully before you enroll. Look at what you spent on copays, prescriptions, and dental work in the past year, and contribute an amount you are confident you will use. If your health situation changes mid-year, you may be able to change your contribution amount if you have a may have access to life event (such as a change in health insurance or the birth of a child).

How to access and use your FSA funds

Most employers provide an FSA debit card that works like a regular debit card at pharmacies, doctor offices, and other medical providers. When you swipe it, the charge is deducted from your FSA balance. Some providers will ask you to verify that the charge is for an may be able to access expense, and you may need to provide a receipt after the transaction.

If your employer does not provide a debit card, you pay for medical expenses out of pocket and then submit a claim for reimbursement. You will need to fill out a claim form (usually available online through your plan's portal) and attach receipts or an explanation of benefits from your insurance company. The plan administrator reviews the claim and deposits the reimbursement into your bank account, typically within one to two weeks.

You can check your FSA balance anytime through your plan's online portal or by calling the plan administrator's customer service number. This helps you track how much you have left to spend before the plan year ends.

Medical FSA versus Health Savings Account

Both accounts offer tax advantages for medical expenses, but they work differently and have different rules. A Medical FSA is available to anyone whose employer offers it, regardless of what health insurance they have. An HSA requires you to be enrolled in a high-deductible health plan (HDHP) — a specific type of insurance with lower premiums and higher deductibles.

The biggest difference is what happens to unused money. FSA money is forfeited at the end of the year (with limited exceptions). HSA money rolls over indefinitely and can be invested like a retirement account. This makes HSAs better for long-term savings, while FSAs are better for predictable annual expenses.

Contribution limits also differ. For 2024, the Medical FSA limit is $3,200 for individuals. The HSA limit is $4,150 for individual coverage and $8,300 for family coverage. If your employer offers both, you can have an HSA and a Dependent Care FSA at the same time, but you cannot have both a Medical FSA and an HSA in the same year.

Enrollment and timing

You can only enroll in a Medical FSA during your employer's open enrollment period, which typically happens once a year in the fall for coverage beginning January 1. If you are a new employee, you usually have 30 to 60 days from your hire date to enroll. If you miss open enrollment and do not have a may have access to life event, you must wait until the next open enrollment period to join.

may have access to life events that let you enroll or change your contribution mid-year include marriage, divorce, birth or adoption of a child, loss of other health coverage, or a significant change in your health care costs. You must request the change within 30 to 60 days of the event (rules vary by employer).

When you enroll, you choose your contribution amount for the entire plan year. You cannot change it again unless you have a may have access to life event. This is why estimating your medical expenses carefully during enrollment is important — you are locked in for the year.

Frequently Asked Questions

Can I use my FSA debit card at any pharmacy or doctor's office?

Most pharmacies and medical providers accept FSA debit cards, but not all do. Before you visit a new provider, confirm they take FSA payments. If they do not, you can pay out of pocket and submit a receipt to your plan administrator for reimbursement. Some providers may ask you to verify the expense is medical in nature before processing the card.

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

You lose access to any unspent money in your FSA when you leave your job. You have until the end of the plan year to submit claims for expenses you incurred while employed, but you cannot add new contributions or carry the balance forward. If your new employer offers an FSA, you can enroll during their open enrollment period, but it is a separate account.

Can I use my FSA to pay for my spouse's or child's medical expenses?

Yes. You can use your FSA to pay for medical expenses of your spouse and any dependent children, even if they are not covered under your health insurance plan. The expense must still be may be able to access under IRS rules, and you will need receipts to prove it.

Do I need receipts to use my FSA debit card?

When you swipe your FSA debit card, the transaction usually goes through without a receipt requirement at that moment. However, your plan administrator may ask you to provide a receipt later to verify the expense was medical in nature. Keep all receipts for at least three to five years in case you are asked to prove the expense.

Can I withdraw money from my FSA without using it for medical expenses?

No. FSA funds can only be used for may be able to access medical expenses. If you withdraw money for non-medical purposes, you will owe income tax on the amount withdrawn plus a 20% penalty. The only exception is if you leave your job or your employer terminates the FSA plan — in those cases, you may be able to access remaining funds under specific circumstances, but this varies by plan.