The invention disclosed herein provides an apparatus and method for securely collecting, storing, and disposing of documents by attaching a reusable, secure, lockable closure to a cardboard receptacle box. The lockable closure has a slot in the top to allow documents to be deposited in the box. Two opposing side surfaces of the lockable closure have an interior lip that engages the box flap in such a way as to prevent the unwanted removal of the closure. The closure can be secured to the box with a locking seal such as a cable tie through locking holes located on the top surface and two opposing sides of the lockable closure as well as the box flaps and box sides. A hole allows removal of the lockable closure by exerting pressure on the flap. The disclosed method provides the steps of providing a single lockable closure, a plurality of receptacle boxes, and a number of locking seals capable of fitting through the holes. The single, reusable, locking closure is placed on a receptacle box, which is sealed, documents are placed into the box through the slot. When the box is full, the locking seals are removed and the box is closed secured with its internal flaps and shipped for destruction or recycling. The same lockable closure is then placed on a different box bottom to repeat the process.