HSAs and FSAs Explained

Why This Matters

HSAs and FSAs both let you set aside money for health care costs before taxes are taken out, which can meaningfully lower what you actually pay for care. But the two accounts are built on very different rules, and mixing them up can lead to lost money, either through a missed contribution deadline or forfeited funds at year-end.

Once you understand the difference, choosing a contribution amount (or deciding whether to use these accounts at all) becomes a much more confident decision instead of a guess made quickly during open enrollment.

Core Principle

An HSA and an FSA both let you pay for health costs with pre-tax dollars, but they are built on opposite assumptions about whether that money stays yours if you don't use it.

What Problem These Accounts Solve

Both a Health Savings Account (HSA) and a Flexible Spending Account (FSA) let you contribute money before it's taxed, then use it tax-free for qualified medical expenses like copays, prescriptions, dental care, and vision care. In effect, they discount your health spending by the amount you'd otherwise have paid in taxes on that money.

Check this: Ask whether your employer offers either account, not every employer offers both, and offering one doesn't guarantee the other.

Eligibility: Why Your Health Plan Determines Which Account You Can Use

You can only contribute to an HSA if you're enrolled in an IRS-qualifying High Deductible Health Plan (HDHP), this is a strict eligibility rule, not a preference. If your plan isn't an HDHP, you're not eligible for an HSA no matter how much you'd like to use one.

An FSA generally doesn't require a specific plan type, but there's an important interaction: if you're contributing to an HSA, you typically can't also have a general-purpose FSA in the same year (a Limited Purpose FSA, restricted to dental and vision expenses, is often the exception offered alongside an HSA).

Check this: Confirm whether your current or offered health plan is HDHP-qualified, this is usually stated directly in your plan name or enrollment materials, before assuming you can choose either account.

Ownership and Portability

An HSA is owned by you, like a personal bank account. The money is yours permanently, it moves with you if you change employers or health plans, and unused funds simply carry over year after year with no expiration.

An FSA is owned by your employer's plan. It's tied to your employment and plan year, and in most cases, if you leave your job, unused FSA funds do not come with you, though the money you already used earlier that plan year stays used, since your full annual election is typically available from day one.

Check this: If you're weighing a job change, ask your current FSA administrator what happens to your account and any remaining balance upon your departure date.

Contribution Limits and How They Work

Both accounts have annual IRS contribution limits that are adjusted most years, always confirm the current-year figures on IRS.gov or your plan documents rather than relying on last year's numbers. As a general reference point, recent HSA limits have been in the range of roughly $4,300 for individual coverage and $8,550 for family coverage, with an extra catch-up amount for those 55 and older; recent FSA limits have been in the range of roughly $3,300.

For HSAs, contributions can come from you, your employer, or both, but the combined total counts toward the same annual limit. Employer HSA contributions are a real form of compensation worth factoring into your total pay picture.

Check this: Look up the current-year contribution limits before open enrollment, and check whether your employer contributes anything to your HSA, that amount reduces how much room you have left to contribute yourself.

Use-It-or-Lose-It vs. Rollover: What Happens to Unused Money

FSA funds are generally subject to a use-it-or-lose-it rule: unused money is forfeited at the end of the plan year, unless your employer offers a limited carryover amount or a short grace period into the next year (not all employers offer these, and the amounts are capped). This is why FSA elections should be based on a realistic estimate, not a guess.

HSA funds have no such deadline. Unused money rolls over indefinitely, year after year, and can often be invested for long-term growth once your balance passes a certain threshold, some people use an HSA as a supplemental retirement account for future medical costs, a connection covered in the workplace retirement lesson.

Check this: If you have an FSA, check your specific plan documents for whether it offers a carryover or grace period, and note the exact deadline so you don't lose unused funds.

How the Pieces Work Together

This comparison summarizes the core differences:

Your health plan choice (covered in the previous lesson) determines HSA eligibility, and your FSA or HSA election is typically locked in at open enrollment, so this decision connects directly to both.

A Realistic Example

Sam is choosing a health plan and account combination for the year ahead. Option one is a PPO paired with an FSA; option two is an HDHP paired with an HSA. Sam knows their child will likely need orthodontic work this year, a fairly predictable expense of about $2,500 out of pocket.

Because the expense is predictable and falls within one plan year, an FSA is a reasonable fit, Sam can elect close to that amount, knowing it will be used and won't be forfeited. If Sam instead expected unpredictable, spread-out expenses rather than one known cost, the HSA's rollover feature would reduce the risk of over-electing and losing money.

Sam elects $2,400 into the FSA, slightly under the expected expense to avoid any risk of forfeiting unused funds, and pays the remaining balance out of pocket. The decision here isn't about which account is 'better' in general, it's about matching the account's rules (immediate use vs. long-term flexibility) to the shape of Sam's actual expenses.

Common Myths About HSAs and FSAs

Frequently Asked Questions