What a Health FSA Really Saves You, With the 2026 Numbers

A health flexible spending arrangement (FSA) saves you the income tax and payroll tax on the money you put in, which for many employees is between about 20 and 30 cents per dollar. The catch is that unused money is generally lost, so the real question is how much of your election you will spend. The math below shows the break-even point.

1. The rules, from the IRS

Publication 969 describes a health FSA as an employer-established benefit plan. You choose an amount to be withheld from your pay, in what the IRS calls a salary reduction agreement. The publication states: "You don't pay federal income tax or employment taxes on the salary you contribute." Self-employed people are not eligible.

For 2026, the IRS announced that the limit on voluntary salary reductions to a health FSA rises to $3,400, up $100 from 2025. If a plan permits a carryover of unused money, the maximum carryover for plan years beginning in 2026 is $680. The 2025 figures in Publication 969 are $3,300 and $660.

On what happens to leftover money, Publication 969 says FSAs are generally "use-it-or-lose-it" plans. A plan can offer either a grace period of up to 2 1/2 months or a limited carryover, and the employer is not permitted to refund the balance to you. The plan decides which feature, if any, it has, so check your plan document.

You also have access to the full annual election early. The publication says you must be able to receive the maximum reimbursement at any time during the coverage period, regardless of how much you have contributed so far.

2. How much tax does the election avoid?

Two kinds of tax are skipped, according to the IRS:

1. Federal income tax, at your marginal rate. For a single filer in 2026 the rates are 10%, 12%, 22%, and higher, with the 12% rate applying to taxable income from $12,401 to $50,400 and the 22% rate from $50,401 to $105,700.
2. Payroll tax. IRS Topic 751 lists 6.2% for Social Security and 1.45% for Medicare on the employee side, a combined 7.65%. Social Security tax applies only up to a wage base of $184,500 in 2026, so very high earners may not save the 6.2% part on the dollars above that.

State and local income tax treatment varies and is not included here.

Assume the maximum 2026 election of $3,400:

So the $3,400 costs you $2,731.90 of take-home pay at 12%, or $2,391.90 at 22%.

3. The break-even point

You come out ahead only if the money buys things you would have bought anyway. Suppose you elect C and use U of it on qualified expenses. Your cost in take-home pay is C x (1 - total tax rate), and what you receive is U in covered purchases. At a combined rate of 29.65% (22% plus 7.65%), the cost of a $3,400 election is $2,391.90.

Break-even use = 1 - 0.2965 = 70.35% of the election, or about $2,392 of spending.

At a combined rate of 19.65% (12% plus 7.65%), break-even use is 80.35% of the election, about $2,732 on a $3,400 election.

The cost of overestimating is steep. If you elect $3,400 at the 22% bracket and use only $2,000, you receive $2,000 of value for $2,391.90 of take-home pay: a net loss of about $392. Electing $2,000 and using all of it would have cost $1,407 of take-home pay for the same $2,000 of care, a gain of about $593.

4. What counts as a qualified expense

Publication 969 says qualified medical expenses are those specified in the plan that would generally qualify for the medical and dental expense deduction. Over-the-counter medicine, with or without a prescription, and menstrual care products are treated as covered expenses. Expenses for you, your spouse, and your dependents qualify. The plan reimburses only expenses incurred during the coverage period, and it needs a statement from an independent third party showing the expense and that it was not paid by other coverage. The plan cannot advance money for future expenses.

5. A way to choose the amount

1. List expenses that are close to certain in the plan year: recurring prescriptions, copays for ongoing care, glasses or contacts, dental work already scheduled.
2. Add only the part of uncertain expenses you would bet on, not the whole range.
3. Elect that total, not the plan maximum.
4. Check whether your plan has a grace period or carryover, and what its deadline for claims is.

Confirm the cap and the plan's deadlines with your employer. The figures here are as of October 2026.

6. Key takeaways

• A health FSA avoids federal income tax and payroll taxes on the salary you contribute, per IRS Publication 969.
• The 2026 contribution limit is $3,400, with a maximum carryover of $680 if the plan allows one.
• At the 22% bracket plus 7.65% payroll tax, a full election saves $1,008.10; at 12% it saves $668.10.
• You break even when you use about 70% of your election at the 22% bracket, and about 80% at the 12% bracket.
• Unused money is generally forfeited unless your plan has a grace period or carryover, so elect what you expect to spend.

This is general information, not tax or benefits advice. Plan rules vary by employer.