Why can’t my unused contributions to Qualified Parking or Mass Transportation plans be returned upon termination of employment?

The IRS states that when an employee voluntarily agrees to reduce compensation in exchange for benefits under a Qualified Parking plan or a Mass Transit plan, federal tax law treats the transportation benefits as benefits provided by the employer and not as benefits purchased by the employee. The benefit allows for the elected benefits not to be subject to taxation. If an employee could at any time get cash instead of these benefits, the employee would be treated as constructively receiving the benefits as compensation and the benefits’ full value would become taxable.