This work discusses waste paper generation in IT environments and the need to reduce the output of reports, source codes and forms in Brazilian governmental institutions to carry out a true policy of sustainability. Green IT is tackled from the premise that paper is the most bulky solid waste daily generated by informatics and the most easily controllable by people. The authors explain a green IT management model which combines finance and cleaner production so that it makes possible to rescue ethical values little remembered today at governmental level, thus keeping public treasury. Present work also explains the mathematics of the model including a preliminar simulation to clarify basic ideas.