How Much Should You Put in Your FSA? A Simple Way to Decide

Short answer: put in what you can confidently spend. For most people that means adding up your predictable medical costs for the year — copays, prescriptions, dental, vision, contacts — then adding the eligible wellness items you already know you'll buy, and electing that number rather than the maximum. For 2026 the IRS cap on a health FSA is $3,400, but the cap is not a target. It's a ceiling.

Open enrollment has a way of arriving fast, and the FSA election box is the one people stare at the longest. Too little and you leave tax savings on the table. Too much and you're scrambling in December. Here's a calmer way to land on a number.

What is an FSA, in plain English?

A health Flexible Spending Account lets you set aside money from your paycheck before taxes are taken out, then spend it on qualified medical expenses. Because the money never gets taxed, a $500 purchase effectively costs you less than $500 — how much less depends on your tax bracket.

The catch is that you choose your contribution amount once, during open enrollment, and you're generally locked in for the plan year unless you have a qualifying life event like a marriage, birth, or job change. That's why the number matters.

How much can you put in an FSA for 2026?

The 2026 health FSA limit is $3,400 per employee, up $100 from 2025. If you and your spouse each have your own FSA through your own employers, each of you can elect up to that amount. Employers are allowed to set a lower cap than the IRS maximum, so check your plan documents rather than assuming you get the full $3,400.

HSAs are different accounts with different rules. For 2026 the HSA limits are $4,400 for self-only coverage and $8,750 for family coverage, with an extra $1,000 catch-up if you're 55 or older. If you're not sure which account you actually have, our guide to paying with an FSA or HSA card walks through the differences.

How do you figure out your own number?

Start with what's already scheduled

Write down the medical spending you know is coming. Prescription refills. Your kid's orthodontia. The dental crown you've been putting off. Contact lenses or a new pair of glasses. Copays for a specialist you see every quarter. These are the safest dollars to put in an FSA because they're going to happen whether you plan for them or not.

Look back before you look forward

Pull last year's spending. Most FSA administrators show a full claim history in your online portal, and your pharmacy can print an annual prescription summary. What you actually spent last year is a far better predictor than what you think you'll spend this year. If last year was unusually heavy or unusually light, use the year before as a sanity check.

Add the eligible things you keep meaning to buy

This is where most people under-elect. Plenty of everyday health items qualify — bandages, sunscreen, thermometers, first aid supplies, and physical therapy devices like red light and infrared therapy tools. If you've been meaning to do something about your knee, your lower back, or your feet, that's a real, plannable expense.

Some rough anchors from our catalog, so you can build a realistic line item:

• 3-in-1 Torch — $84.99
• Red Light Therapy Belt — $119.99
• HL300 infrared sauna blanket — $159.99
• FX300 panel — $199.99
• Red Light Therapy Slippers — $199.99
• LX300 LED face mask — $239.99
• FX500 panel — $269.99

Not sure which one fits your situation? The device finder quiz takes about a minute.

Then subtract a cushion

Once you have a total, shave 10 to 15 percent off it. Life is unpredictable in both directions, and it is far more comfortable to run out of FSA money in November than to have $400 sitting there on December 20th.

What happens to FSA money you don't spend?

It depends on what your employer chose. Health FSAs come with three possible endings, and your plan can only have one of them:

1. Carryover. You can roll up to $680 of unused 2026 funds into the following plan year. Anything above that is forfeited.
2. Grace period. You get an extra two and a half months after the plan year ends to spend down the balance, but nothing carries over.
3. Neither. Whatever's left at the end of the plan year is gone.

Most plans also have a run-out period — a window after the year ends to submit claims for expenses that happened during the year. That's a filing deadline, not extra spending time. Two different things, and people mix them up constantly.

Is it better to over-elect or under-elect?

Under-elect, slightly. If you guess low, you simply pay for the extra expenses with after-tax dollars, which is what would have happened anyway without an FSA. If you guess high, you either forfeit the money or make a rushed purchase you don't need. The downside is not symmetrical.

One important exception: the FSA is unusual in that your full annual election is available on day one, even though contributions come out of your paychecks gradually. If you know you have a big eligible expense in January, that's an argument for electing more, not less.

Where does red light therapy fit in a health budget?

It fits in the same place as a TENS unit, a knee brace, or a heating pad: a home tool you use consistently for ongoing aches, alongside whatever your doctor or physical therapist recommends. It is not a replacement for medical care, and it isn't a cure for anything.

What the research supports is modest but real. Photobiomodulation — the clinical term for red and near-infrared light therapy — has been studied for musculoskeletal pain for decades. A systematic review and meta-analysis in Clinical Rehabilitation examined low-level laser therapy for nonspecific chronic low back pain and reported pain improvements versus placebo. A randomized controlled trial of LED photobiomodulation in working nurses looked at the same problem using LED rather than laser sources. And a broader literature review on photobiomodulation for pain and inflammation summarizes the proposed mechanisms and where the evidence is strongest. Trials vary a lot in dose, wavelength, and study quality, so treat these as encouraging rather than conclusive.

Practically, that means budgeting for a device makes sense if you have a persistent, familiar ache you're willing to spend ten minutes a day on. It makes less sense as a one-time December purchase to burn leftover funds.

Frequently asked questions

Can I change my FSA election mid-year?

Usually only after a qualifying life event — marriage, divorce, birth or adoption, a change in employment status, or a change in your spouse's coverage. Outside of those, your election is locked for the plan year. Contact your HR or benefits administrator to confirm what your plan allows.

Does the $680 carryover count against next year's contribution limit?

No. Carried-over funds sit on top of whatever you elect for the new year, so you could have more than $3,400 available. Only your fresh election counts toward the annual cap.

Do I need a doctor's note to buy red light therapy with FSA funds?

Usually not for devices marketed for pain relief, which are commonly treated as eligible medical equipment. Some administrators are stricter than others and may ask for documentation. If yours does, our post on using an FSA or HSA card for red light therapy covers what to send.

What if I contribute more than I spend and I leave my job?

With a health FSA you generally can't take the balance with you, though you may be able to continue it through COBRA in some situations. Notably, you also don't have to repay an FSA you've overspent — if you used the full election and left in March, that money is typically yours. HSAs work the opposite way: the account is always yours.

Should I use my FSA or my HSA first?

If you have both — usually a limited-purpose FSA alongside an HSA — spend the FSA first, since it has a deadline and the HSA doesn't. HSA dollars can stay invested and follow you for life.

Is there a minimum FSA contribution?

Most employers set a small minimum, often somewhere around $100 to $250, but it varies. Your benefits summary will list it.

The bottom line

Add up what's predictable, check it against last year, add the eligible purchases you've been postponing, then trim a little. That's your number. It'll almost never be the maximum, and it doesn't need to be — the goal is pre-tax dollars spent on things you'd have bought anyway, not a bigger balance for its own sake.

If pain relief is on that list, start with the device finder quiz or browse the FSA/HSA eligible collection so you can price it out before you commit to an election.

Lights on, pain off.

This article is for general education and is not medical advice. Red light therapy devices are intended for general wellness and are not intended to diagnose, treat, cure, or prevent any disease. Always check with a qualified healthcare provider before starting a new therapy.