FSA Planner Calculator

An FSA election is a bet on your own medical spending for the year

A flexible spending account offers a genuine tax advantage — contributions come out of your paycheck before tax, directly reducing taxable income — but it comes with a real constraint that an HSA does not share: money elected into an FSA and not spent (beyond a limited exception) is forfeited back to the employer at year-end. That makes the election amount itself a meaningful decision, not simply “elect the maximum for the biggest deduction.”

This calculator compares your planned election against your expected medical spending directly, so the forfeiture risk is visible before the plan year locks in your election rather than discovered as a surprise the following January.

The 2026 contribution limit, and why it changes most years

The IRS set the 2026 healthcare FSA employee contribution limit at $3,400, continuing the pattern of annual inflation adjustments that has applied to this limit for years. Because this figure moves nearly every year, treat any FSA limit you remember from a prior year with suspicion and re-check current guidance before finalizing an election.

Employers can set a lower cap than the federal limit if they choose, so the actual maximum available to you is whichever is lower — the IRS limit or your specific employer’s plan design.

“Use it or lose it” is real, but most plans soften it somewhat

The strict original rule for FSAs required forfeiting any unused balance at the exact end of the plan year, with no exceptions. Current rules allow employers to offer one of two accommodations, though never both simultaneously on the same plan.

A grace period extends the window to incur new expenses — commonly up to two and a half additional months — using the prior year’s remaining balance, effectively giving more time to spend down funds without extending how much you can elect. A carryover, by contrast, lets a limited dollar amount roll directly into the next plan year’s balance, available alongside whatever you elect for that new year — for 2026, that carryover limit is $680.

Critically, some employer plans offer neither accommodation, reverting to the original strict forfeiture rule — confirm which structure your specific plan actually uses before assuming either protection applies, since this detail meaningfully changes how conservatively to elect.

Building an honest expected-expense estimate

The single most useful input in this calculator, and the one most people guess at rather than actually calculate, is expected annual medical expenses. A more accurate estimate comes from adding up known, predictable costs: recurring prescriptions at their actual annual cost, routine dental and vision expenses if the FSA covers them under your plan design, planned procedures or known upcoming medical needs, and a modest allowance for the ordinary unplanned doctor visit or urgent care trip most households experience at least once a year.

Resist the temptation to inflate this estimate simply to justify a larger election — the tax savings from a larger election are real, but they are not worth much if a meaningful share of the elected amount ends up forfeited entirely.

Why FSA and HSA are not simply two versions of the same account

Beyond the expiration difference, FSA and HSA eligibility work differently: an FSA does not require enrollment in a high-deductible health plan, making it available to people on traditional lower-deductible plans who would not qualify for an HSA at all. Someone not HSA-eligible does not face a real choice between the two — the FSA is the pre-tax medical spending option available to them, full stop, and this calculator’s forfeiture-risk framing is the primary planning tool for them.

For someone who is HSA-eligible and weighing which account to prioritize, the HSA versus FSA comparison runs that specific decision directly, since the two accounts serve genuinely different roles even when both are technically available.

Mid-year changes are more restricted than many people expect

Once an FSA election is made during open enrollment, changing it mid-year generally requires a qualifying life event — a marriage, birth of a child, job loss, or a similar significant change — rather than simply deciding your original estimate was off. This is a meaningfully different flexibility profile than an HSA, where contribution amounts can typically be adjusted at any point during the year through payroll.

That inflexibility is exactly why getting the initial election reasonably close to actual expected spending matters more for an FSA than it would for an account you could freely adjust later, and it is the core reason this calculator exists — modeling the forfeiture risk before the election locks in, rather than after.