"If the FSA has a grace period and the employee has no funds remaining in the FSA at the end of the plan year, then the employee may begin contributing to the HSA at the beginning of the new plan year. However, if the employee has any funds remaining in their FSA at the end of the plan year, then they must wait until the grace period ends to begin contributing to an HSA.... If an employee rolls over any unused FSA funds to the new plan year, they would not be eligible to enroll in or contribute to an HSA. In order to be HSA eligible, the employee would need to spend all of their FSA funds by the end of the plan year or transfer the FSA funds to a limited purpose FSA."