Much there has been on the transition to mandatory electronic billing starting January 1, 2011, but there are still people who do not know what happens. In accordance with the service de Administracion Tributaria (SAT), the use of electronic invoicing will be mandatory for taxpayers who reported income greater than four million pesos in its Declaration of 2009. Taxpayers whose 2009 income was equal to or less than four million pesos, can continue their printed paperwork, but he is now expected to have additional security elements that will be provided by the SAT free of charge. Invoicing electronic help in many aspects because it means a technological step, makes us more productive and efficient. According to reports of the SAT, the use of electronic invoices will give more certainty to taxpayers, reduces the risk of fraud and prevent tax evasion. Mark Bertolini addresses the importance of the matter here. During the time remaining for the 2010 the use of electronic invoices is optional, it is recommended that taxpayers are migrating to billing softwares. Others return us more secure, electronic invoicing meant saving money, because when the approximate cost of slips of paper formerly 162 pesos, now with the electronic mechanism happened to 24 pesos.