HSA vs. FSA: What Actually Changes When You Switch
Both let you pay for medical expenses with pre-tax money. Past that, they work almost nothing alike — who owns the account, what happens to unused funds, and who's even allowed to have one are all different.
Key takeaways
- HSA funds roll over forever and are yours to keep; FSA funds are mostly forfeited at year-end.
- You need a qualifying high-deductible health plan to open an HSA — FSAs have no such requirement.
- Self-employed people can open an HSA directly but can't get an FSA at all.
Side-by-side comparison
| HSA | FSA | |
|---|---|---|
| Who owns it | You. Portable across jobs. | Your employer. Stays behind if you leave. |
| Eligibility to open one | Must be enrolled in a qualifying HDHP | Employer must offer it — no HDHP required |
| 2026 contribution limit | $4,400 self-only / $8,750 family | $3,400 |
| Age 55+ catch-up | +$1,000 | Not applicable |
| Unused funds | Roll over indefinitely, every year | Forfeited at year-end, minus a limited exception (below) |
| Can you invest the balance? | Yes, like a retirement account | No |
| Self-employed? | Can open one directly | Not eligible — FSAs are employer-sponsored only |
The rollover difference is the one that actually matters
An HSA has no "use it or lose it" clock. Money you contribute this year and don't spend is still yours in ten years, growing the whole time. An FSA works the opposite way by design: it's funded for a single plan year, and most employers give you either a short grace period (up to 2.5 months) or a capped carryover ($680 for 2026) to spend down what's left — never both, and never an indefinite balance.
Why you can't just pick whichever you want
The eligibility rule runs through your health insurance, not your preference. HSAs require you to be enrolled in a high-deductible health plan that meets IRS thresholds (for 2026: minimum deductible of $1,700 self-only / $3,400 family). If your employer's plan doesn't qualify as an HDHP, you can't open an HSA no matter how much you'd like the flexibility — an FSA becomes the only pre-tax option if your employer offers one.
Can you have both?
Generally no — enrolling in a standard health FSA disqualifies you from HSA contributions for that period, since the FSA counts as other health coverage. The exception is a "limited-purpose FSA," which some employers pair with an HSA specifically because it only covers dental and vision, not general medical expenses, so it doesn't trigger the disqualification.
Sources: IRS Revenue Procedure 2025-19 (2026 HSA limits), IRS Publication 969.