Can an employer allow an employee to elect an HSA mid-year if offered as a new benefit under the employer's Cafeteria Plan?

An employer may offer an HSA mid-year as a new benefit under a Cafeteria Plan and allow the employee to elect an HSA, so long as their election for the HSA is made on a prospective basis. In such a situation, however, they may have other coverage under the Cafeteria Plan that cannot be changed (e.g., coverage under a health flexible spending account) that may prevent them from being an eligible individual with respect to the HSA.