Net Fixed Asset Tax (ITAN for its acronyms in Spanish) was created with some important omissions as the definitions of net asset (a component of tax basis). This situation hasn´t changed so far. For this reason, Tax Authority has been issuing opinions with their own judgement about the tax treatment of an item. Sometimes, this opinion differs from a previous one, issued by the same authority. In this context, we explain and analyze the criteria applied in ITAN Law, similar taxes in America Latina and the most significant opinions issued by Tax Authority related to ITAN, in order to understand the scope of this type of tax. Then, we analyze the accounting rules related to net asset and right-of-use-asset. Finally, we analyze the tax consequences after considering the right-of-use-asset as part of ITAN tax basis. At the end of this work, we suggest a legal proposal to reduce the uncertain...