A method and system for generating a completed payment document ready for signature in image form and enabling signature in image form, storing the image and providing a printed copy of the document including the signature. A write input device for showing the image and enabling the signature includes a transparent interactive digitizing element with writing stylus, a display module positioned beneath the digitizing element and visible therethrough, and optionally a magnetic stripe reader for providing document-related information for the display. The device is embodied in a system which also includes a point of sale terminal, a printer for printing records of transactions processed by the system and a controller operatively coupled to other elements of the system.