This research was developed based on three purposes: discuss the main difficulties encountered in implementing the first financial statements in accordance with the International Financial Reporting Standards (IFRS); present the main provisions of the Interpretation of IFRIC 12, which is intended to guide accounting of concession contracts by concessionaires of public services; and discuss the possible impact of its adoption in the companies that provide switched fixed telephone services (STFC). This is an exploratory, qualitative and theoretical study, based on review of documents and literature, followed by questionnaires and interviews with a small sample of organizations impacted by the adoption of this regulamentation, as also experts in this area, like university professors. IFRIC 12 details the accounting treatment of the rights and duties of infrastructure that is the object of the concession contract, the recognition and measurement of operations related to those contracts which significantly change the accounting methods used by Brazilian Corporate Law until then. The main impacts of the adoption of IFRIC 12 by the concessionaires of STFC companies operating in Brazil will be: reclassification of Property, Plant and Equipment used to provide fixed telephone services to Intangible Assets and Financial Assets, since this standard does not allow that the infrastructure related to the concession contract to be recognized as Property, Plant and Equipment, and changes in revenue recognition related to these contracts. According to the results obtained, this subject is still controversial and there is no uniformity among stakeholders about its applicability or not by the Brazilian Companies that provide STFC, although its definition is mandatory for financial statements for the year ending 31 December, 2010, as it must be submitted to the Brazilian Securities Commission (CVM) by March 31, 2011.