A limited purpose FSA is a type of flexible spending account that can only be used for dental and vision expenses. To have one, you must be enrolled in a high deductible health plan (HDHP). Your money goes in and comes out tax-free, but it’s not portable if you change jobs. You can only set your contribution once a year, and any unused funds by year-end may be lost, though some employers allow extra time or carryover. LPFSA’s are ideal for consumers with high dental and vision expenses.