An FSA is not a health savings account, though both let you set aside pre-tax money for medical costs

A Flexible Spending Account (FSA) and a Health Savings Account (HSA) are separate accounts with different rules, different employers, and different ways the money works. The confusion is understandable—both reduce your taxable income and both pay for medical expenses. But they operate under different federal programs, have different contribution limits, different rules about what happens to unused money, and different may be able to access requirements. If you have one, you cannot have the other in the same year.

The key difference: an HSA is yours to keep and grow year after year. An FSA is a use-it-or-lose-it account tied to your job. Money left over in an FSA at the end of the plan year does not roll into the next year—it stays with your employer's plan. An HSA rolls forward indefinitely, and you can invest it like a retirement account.

Key Takeaways

  • FSAs and HSAs are two separate account types under different federal rules, and you cannot have both in the same calendar year.
  • FSA money does not roll over to the next year (with limited exceptions), while HSA money stays in your account indefinitely and can be invested.
  • An FSA is offered by your employer and is tied to your job; an HSA is owned by you and stays with you even if you change jobs.
  • FSAs have lower contribution limits than HSAs, and FSAs do not require a high-deductible health plan, while HSAs do.

How FSAs and HSAs differ in structure and ownership

An FSA is a benefit plan run by your employer. Your employer sets it up, decides whether to offer it, and controls the rules within federal limits. When you leave that job, the FSA account closes. Any money left in it at the end of the plan year (usually December 31) is forfeited—your employer keeps it. Some employers allow a grace period of up to 2.5 months into the next year, or a carryover of up to $610 (as of 2024), but this is optional and varies by plan.

An HSA is owned by you, not your employer. Your employer may contribute to it, but the account is in your name and you control it. If you change jobs, the HSA comes with you. Money in an HSA rolls forward year after year and can be invested in stocks, bonds, or mutual funds, much like a retirement account. You can withdraw it at any time for any reason—though non-medical withdrawals before age 65 are taxed as income and hit with a 20% penalty.

Because an HSA is portable and grows over time, it functions as a long-term savings tool. An FSA is designed for predictable, near-term medical expenses within a single plan year.

Contribution limits and may be able to access rules

FSA contribution limits are set by federal law but vary by employer plan. For 2024, the limit is $3,300 per year for individual coverage. Your employer may set a lower limit. You contribute through payroll deductions, and the money comes out before taxes are calculated, reducing your taxable income.

HSA contribution limits are higher: $4,150 for individual coverage and $8,300 for family coverage in 2024. These limits are set by federal law and do not vary by employer. You can contribute through payroll, or you can contribute on your own and deduct it on your tax return.

To open an HSA, you must be enrolled in a high-deductible health plan (HDHP)—a specific type of insurance with a minimum deductible set by federal law. An FSA has no such requirement. You can have an FSA with any health insurance plan, including a traditional PPO or HMO. This is why some people have an FSA but not an HSA: their employer does not offer an HDHP, or they chose a different plan.

The use-it-or-lose-it rule and what happens to leftover money

The most important practical difference is what happens to money you do not spend. In an FSA, if you do not use the money by the end of the plan year, you lose it. This is called the use-it-or-lose-it rule. Your employer keeps the forfeited funds. Some employers allow a grace period (an extra 2.5 months into the next year to spend the money) or a carryover (up to $610 in 2024), but neither is required, and rules vary widely by plan.

In an HSA, there is no use-it-or-lose-it rule. Money rolls forward indefinitely. If you do not spend it this year, it is still there next year, and the year after that. This makes an HSA a true savings account for future medical costs, including costs in retirement.

Because of this difference, FSAs work best when you can predict your medical expenses fairly accurately. If you know you will spend $2,000 on copays, prescriptions, and dental work this year, you can contribute $2,000 to an FSA and use it all. If you are uncertain, an HSA is safer because unused money does not disappear.

What each account can pay for

Both FSAs and HSAs can pay for the same types of medical expenses: copays, coinsurance, deductibles, prescription drugs, dental work, vision care, mental health services, and many other costs. Both accounts use the IRS definition of may have access to medical expenses, which is quite broad.

However, some expenses are covered by one but not the other. For example, over-the-counter medications (like cold medicine or pain relievers) can be paid for with an HSA without a prescription, but an FSA typically requires a prescription. Dependent care (like daycare) can be paid for with a dependent care FSA, but not with an HSA. The rules are similar but not identical, so check your specific plan documents.

Can you have both an FSA and an HSA?

No. Federal law prohibits you from having an FSA and an HSA in the same calendar year. The reason is that both accounts reduce your taxable income, and the IRS does not allow you to double-dip.

However, there is one exception: a limited-purpose FSA (also called a health FSA or dental/vision FSA) can be used alongside an HSA. A limited-purpose FSA covers only dental and vision expenses, not general medical expenses. Because it does not cover the same ground as an HSA, the IRS allows both. If your employer offers a limited-purpose FSA, you can contribute to both it and an HSA in the same year.

If you currently have an FSA and want to switch to an HSA, you must wait until the next plan year. You cannot have both running at the same time.

Which account makes sense for your situation

Choose an FSA if your employer offers one and you have predictable medical expenses you know you will incur within the next 12 months. FSAs are useful for people with regular prescriptions, ongoing dental work, or scheduled procedures. The lower contribution limit ($3,300) is enough for many people's annual costs.

Choose an HSA if your employer offers a high-deductible health plan and you want to build long-term savings for future medical costs. HSAs are better if you are healthy and do not spend much on medical care now but want to set money aside for later. The higher contribution limit and the ability to invest the money make HSAs powerful retirement savings tools.

If your employer offers both, you must choose one or the other (unless the FSA is limited-purpose). Consider your health, your expected medical costs, and whether you want the money to roll forward. If you are unsure, ask your benefits administrator which option makes sense for your situation.

Frequently Asked Questions

Can I use my FSA money for anything my HSA would cover?

Mostly yes—both accounts cover copays, prescriptions, dental, and vision. But some expenses differ. Over-the-counter medications usually need a prescription to be covered by an FSA but not an HSA. Check your FSA plan documents for the exact list of covered expenses.

What happens to my FSA money if I leave my job mid-year?

You lose access to the account when ready. Any money left in it is forfeited to your employer. Some employers allow you to continue the FSA through COBRA (the federal law that lets you keep group health insurance after leaving a job), but you would have to pay the full premium yourself. Check with your former employer's benefits office.

Can I withdraw HSA money for non-medical expenses?

Yes, but it comes with a cost. Withdrawals for non-medical expenses are taxed as ordinary income and hit with a 20% penalty if you are under 65. After 65, you can withdraw for any reason without the penalty, though non-medical withdrawals are still taxed as income.

If I have an FSA, can I open an HSA later in the year?

Not in the same calendar year. You must wait until January 1 of the next year. If you want to switch, you would stop contributing to the FSA at the end of the current plan year and start an HSA in the new year.

Do I have to use my FSA or HSA by a certain date each year?

FSA money must be used by the end of the plan year (usually December 31), with a possible grace period of 2.5 months. HSA money has no important date—it rolls forward indefinitely. This is one of the biggest practical differences between the two accounts.