You must enroll each year to participate.
Because FSAs can give you a significant tax advantage, they must be administered according to specific IRS rules:
Health care FSA: Unused funds of up to $500 from one year can carry over to the following year. Carryover funds will not count against or offset the amount that you can contribute annually. Unused funds over $500 will NOT be returned to you or carried over to the following year.
Dependent care FSA: Unused funds will NOT be returned to you or carried over to the following year.
You can incur expenses through [DATE], and must file claims by [DATE].