What's the difference between an FSA and an HSA, and which should I pick at enrollment?

Both let you pay medical costs with pre-tax dollars, but the HSA is far more powerful and flexible. An HSA requires a high-deductible health plan, but the money is yours forever — it rolls over every year, grows invested tax-free, and becomes a stealth retirement account after 65. A Flexible Spending Account is offered with most plan types, but it's largely "use it or lose it," with only a small carryover or grace period, and it doesn't follow you if you leave the job. In 2025 you can put up to $4,300 self-only or $8,550 family into an HSA; FSAs cap around $3,300. If you're on an HDHP, prioritize the HSA and let it grow. An FSA still makes sense for predictable, near-term costs you'll definitely incur that year — estimate conservatively so you don't forfeit unspent money. You generally can't have a general-purpose FSA and HSA simultaneously.