HSA vs FSA Calculator: Which Saves You More in 2026?

Both accounts reduce your taxes on healthcare spending. But they work very differently, and most people with access to an HSA are better off using it.

The key difference: an FSA is a spending account. An HSA is a savings and investment account. Money left in an FSA at year-end mostly disappears. Money left in an HSA compounds indefinitely.

2026 Contribution Limits

FSA limits are per employer, not per person. If both spouses have access to FSAs at their jobs, each can contribute $3,300.

Immediate Tax Savings Comparison

At 25% combined tax rate (22% federal + 3% state):

On the FSA, you save $825 per year on $3,300 in contributions. On the HSA, you save $1,075 on $4,300.

The 20-Year Difference

The real gap is compounding. If you invest your HSA balance in index funds at 7% and carry the balance forward each year, here is what happens versus spending an equivalent FSA contribution on healthcare each year:

The FSA has no balance because it either gets spent each year or forfeited. The HSA can accumulate into a retirement healthcare fund.

The $188,000 at year 20 is not a hypothetical. It is what happens when you max an HSA, invest in low-cost index funds, and pay healthcare expenses from your regular income instead.

When an FSA Wins

An FSA makes sense when:

• Your employer only offers a traditional (non-HDHP) health plan and an FSA. You cannot have an HSA without an HDHP.
• You have predictable, significant healthcare expenses that you will definitely spend this year
• You cannot afford to pay out-of-pocket and let the HSA grow

A Dependent Care FSA is in a different category. If you have young children and spend more than $3,300/year on daycare or after-school care, the Dependent Care FSA is worth maxing regardless of your health insurance situation.

FSA Grace Period and Rollover Rules

Most FSAs have a use-it-or-lose-it rule, but there are two exceptions:

1. 2.5-month grace period: Employer allows spending until March 15 of the following year
2. $640 rollover: Employer allows carrying up to $640 into the next plan year (2026 limit)

Your employer picks one option or neither. Check your Summary Plan Description.

HSA Eligibility Requirements

To open and contribute to an HSA, you must:

• Be enrolled in a High Deductible Health Plan (HDHP)
• Not be enrolled in Medicare
• Not be claimed as a dependent on someone else's return

A 2026 HDHP has a minimum deductible of $1,650 (individual) or $3,300 (family) and maximum out-of-pocket of $8,300 (individual) or $16,600 (family).

See Best Savings Accounts for comparison if you are looking at cash-equivalent HSA options.

Use the CalcMoney Compound Interest Calculator to model your HSA's growth over time with different contribution and return assumptions.

Frequently Asked Questions

Can I have both an HSA and an FSA?

Not both a standard Health FSA and an HSA at the same time. However, you can have an HSA and a Limited Purpose FSA (which covers only dental and vision) or a Dependent Care FSA. Check with your employer on what combinations are available.

What happens to HSA money if I switch from an HDHP to a traditional plan?

Your existing HSA balance remains yours and continues to grow tax-free. You just cannot make new contributions while not on an HDHP. The money can still be used for qualified medical expenses at any time.

Can I invest my FSA balance in mutual funds?

No. FSA balances sit in cash and cannot be invested. This is one of the structural reasons the HSA is more powerful for long-term wealth building.

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