About half of flexible spending account users forfeit funds annually. Don’t be one of them. Here’s how to use your benefits before year-end. It’s almost the end of the year, and for many, that means health flexible spending account (FSA) funds are set to expire. FSAs allow employees to set aside pretax money to pay for healthcare expenses such as copays, some medications, and deductibles. But many people aren’t aware that the funds don’t always roll over into the next calendar year after December 31.