You can place the shipping label on any flat surface of the box. Make sure that it is not on the bottom side of the box. And if the box has a bar code or a QR code on it that requires scanning, the label should not cover any part of it. However, if there is any old barcode on the box that is not related to the product inside the box, you can either cover it with the label or strike them off with a permanent marker. One thing to remember while placing a label on a shipping box is to follow the rules of your postal service. It is common for them to have special rules regarding where to place the label.