The amount you contribute to your FSA depends on your household expenses, your tax bracket, and how much you're willing to set aside without touching it

There is no single "right" amount. The IRS sets a maximum annual contribution limit, but you choose how much of that limit to use based on what you actually spend on may be able to access medical and dependent care costs. The limit changes each year: for 2024 it is $3,300 for a medical FSA and $5,000 for a dependent care FSA (or $2,500 if you're married filing separately). For 2025, the medical FSA limit is $3,300 and the dependent care limit is $5,000. These figures are adjusted annually for inflation.

The real decision is not "how much can I put in" but "how much will I actually use." Money you don't spend by the end of the plan year is forfeited — there is no rollover to next year (with a narrow exception for medical FSAs that offer a grace period). This is called the use-it-or-lose-it rule, and it makes FSA contribution planning different from other retirement or savings accounts.

Key Takeaways

  • The IRS sets a maximum you can contribute each year ($3,300 for medical FSA in 2025, $5,000 for dependent care FSA), but you choose the actual amount based on your expected spending.
  • Money left unspent at the end of your plan year is forfeited unless your employer offers a grace period or carryover option for medical FSAs.
  • To estimate your contribution, add up what you paid out of pocket for may be able to access expenses in the past year, then adjust for changes in your situation.
  • You can change your FSA contribution amount only during open enrollment or if you have a may have access to life event like a birth, marriage, or job change.

How to estimate what you'll actually spend

Start by looking at your medical and dependent care receipts from the past 12 months. For a medical FSA, this includes copays, coinsurance, deductibles, prescription costs, dental work, vision care, and other out-of-pocket medical expenses your insurance doesn't cover. For a dependent care FSA, it includes daycare, after-school programs, summer camps, and adult day care for a dependent you claim on your taxes.

Add those costs together. That number is a reasonable starting point for your contribution, because your spending patterns usually don't change dramatically year to year. If you know your situation will change — you're having a baby, your child will start school, you're switching insurance plans — adjust upward or downward accordingly.

Many employers provide a worksheet during open enrollment to help you estimate. Some also let you log into your FSA account and see what you spent in previous years if you had an FSA before.

Why contributing less than the maximum is often the safer choice

The maximum contribution sounds appealing, but it's a trap if you don't actually spend that much. If you contribute $3,300 to a medical FSA and only spend $2,000, you lose $1,300. That's money you already earned and set aside — it straightforward disappears.

Underestimating your spending is less costly than overestimating. If you contribute $2,000 and spend $2,500, you pay the extra $500 out of pocket. That stings, but you keep the money. If you contribute $2,500 and spend $2,000, you forfeit $500 with no way to recover it.

This is why many people contribute conservatively — somewhere between 50 and 75 percent of the maximum, or an amount equal to their actual prior-year spending. Your employer may also offer a grace period (usually 2.5 months after the plan year ends) during which you can still spend down your FSA balance, which gives you a small buffer.

Life changes that let you adjust your contribution mid-year

You can only change your FSA contribution during your employer's open enrollment period, which is usually once a year. However, if you have a may have access to life event, you can make changes outside of open enrollment.

may have access to events include birth or adoption of a child, marriage or divorce, death of a spouse or dependent, significant change in your dependent care costs, loss or gain of health insurance coverage, and a substantial change in your health care needs. You typically have 30 to 60 days from the event to notify your employer and make the change.

If you have a baby mid-year, for example, you can increase your dependent care FSA contribution to account for the new childcare costs. If you switch to a plan with a lower deductible, you might lower your medical FSA contribution because you'll have fewer out-of-pocket costs.

The difference between medical and dependent care FSA contribution strategies

Medical FSA contributions are easier to predict because your medical spending is somewhat consistent — you know roughly what your copays, prescriptions, and routine care cost. Dependent care FSA contributions depend on whether you're paying for childcare, and how much that costs in your area. Daycare costs vary widely by region and provider type.

If you use dependent care, the $5,000 limit (or $2,500 if married filing separately) often matches or exceeds actual spending for one child. Many people max out a dependent care FSA because the expenses are predictable and the limit is high enough to cover them. Medical FSA contributions are more often conservative because medical spending is harder to forecast and the limit is lower.

Some employers offer both types of FSA. You can contribute to each one independently, up to their separate limits.

What happens if you contribute too much and can't spend it

If you reach the end of your plan year with unspent FSA money, it is forfeited. You cannot roll it over to next year, and you cannot withdraw it. The money goes back to your employer or the FSA plan administrator.

Some employers offer a grace period — usually 2.5 months after the plan year ends — during which you can still incur and submit may be able to access expenses. If your plan year ends December 31, a grace period might extend through March 15. This gives you extra time to use the balance, but it does not extend the important date indefinitely.

A small number of medical FSA plans allow you to carry over up to $640 (in 2025) to the next year, but this is rare and only available if your employer chooses to offer it. Check your plan documents or ask your benefits administrator whether your plan includes a grace period or carryover option.

How FSA contributions affect your taxes

FSA contributions are made with pre-tax dollars, meaning the money comes out of your paycheck before federal income tax, Social Security tax, and Medicare tax are calculated. This reduces your taxable income for the year.

If you contribute $2,500 to a medical FSA, you pay roughly 20 to 30 percent less in taxes on that $2,500 (depending on your tax bracket). That's the main financial benefit of an FSA — you save on taxes. The downside is the use-it-or-lose-it rule, which makes it riskier than a savings account.

Your employer handles the tax treatment automatically. You don't have to do anything special on your tax return.

Frequently Asked Questions

Can I change my FSA contribution amount after open enrollment?

Only if you have a may have access to life event like a birth, marriage, divorce, or significant change in your dependent care costs. You typically have 30 to 60 days from the event to request the change. Outside of these events, you're locked into your contribution amount for the entire plan year.

What if I don't spend all my FSA money by the end of the year?

The unspent balance is forfeited. Some plans offer a grace period (usually 2.5 months after the plan year ends) to incur additional expenses, and a few plans allow a small carryover to the next year, but most do not. Check your plan documents to see what your employer offers.

Should I contribute the maximum amount to my FSA?

Not necessarily. Contribute an amount you're confident you'll spend. Underestimating is safer than overestimating because you can pay out of pocket for expenses you didn't budget for, but you cannot recover forfeited FSA money. Most people contribute based on their actual prior-year spending or slightly less.

Do FSA contributions reduce my taxable income?

Yes. FSA contributions are made with pre-tax dollars, so they lower your federal income tax, Social Security tax, and Medicare tax for the year. Your employer handles this automatically through your payroll.

Can I have both a medical FSA and a dependent care FSA?

Yes, if your employer offers both. You can contribute to each one up to their separate annual limits. The medical FSA limit is $3,300 for 2025, and the dependent care FSA limit is $5,000 (or $2,500 if married filing separately).