What is the difference between an HSA and an FSA?
Last updated September 3, 2026.
Both pay medical costs with pre-tax dollars, but an HSA is your personal account - rolls over forever, follows you between jobs, investable, and gated behind a high-deductible plan - while an FSA is your employer's arrangement (per Healthcare.gov), needs no special plan, and is use-it-or-lose-it at plan-year end with at most a small carryover or short grace period. Practical consequences: FSAs reward planning - fund only what you know you will spend (recurring prescriptions, planned glasses, therapy). HSAs reward maximization - fund fully, pay cash if you can, let the balance compound. You generally cannot hold both at once; the narrow exception is a limited-purpose FSA (dental and vision only) alongside an HDHP. Pymander is a free AI doctor, 24/7 by text, and can help you pick and fund the right one.
What to do
- HSA if you have an HDHP: rollover plus investment makes it the stronger account.
- FSA: fund only predictable spending: the year-end cliff is real.
- Leaving a job? FSA dies, HSA follows: plan the FSA drain before your exit date.
- Want both? Limited-purpose FSA only: dental and vision, alongside the HDHP.
Related questions
- Do HSA funds expire?
- What is a health savings account?
- Can I have an HSA with any insurance plan?
- What happens to my HSA when I change jobs?