Unless you are the School Coordinator, all you need to do is send them to school before they expire! If you've got a whole bunch, it's helpful to Coordinator to divide them into bundles of 50.
If you are the School Coordinator, please visit the Submitting Box Tops page for step by step directions. Remember, all receipt scan earnings will be automatically identified and credited to your school’s account online. No action is needed from you to receive your receipt scan earnings during the December and April check runs.