In the study, three different cases where taxpayer registration can be canceled by the tax administration, regulated in Articles 160 and 160/A of the Tax Procedure Law, have been critically examined within the framework of the basic concepts and principles of tax law and criminal law. In the first three parts of the study, the conditions of ex officio cancellation transactions, and in the fourth part, the legal qualities of these transactions are tried to be determined. In this respect, the issues that need to be considered in terms of protecting fundamental rights and freedoms in the process of ex officio cancellation of the taxpayer registration in cases where there is a suspicion or identification that the crime of issuing forged documents has been committed are stated. In the fifth chapter, the problems experienced in connection with the notification in cases of ex officio cancellation are discussed. In this context, in practice, in cases where the taxpayer registration is canceled as a result of the tax inspection, the negative situations caused by the notification of this issue to the taxpayer together with the notification and the request for the books and documents by electronic notification to the persons whose taxpayer registration is canceled are explained. As a result, in cases where the tax registration is canceled ex officio, the problems arising from the legislation or practice have been evaluated and solutions have been presented.