When the enforcement effect of the Additional Corporate Tax created by Law No. 7440 and the Additional Motor Vehicle Tax created by Law No. 7456 in order to compensate for the budget deficits also caused by the earthquakes of 6-7 February 2023, centered in Kahramanmaraş, is examined, it is observed that their legal consequences are retroactive. Although the provisions and consequences of these laws are retroactive, the rule in the application of tax laws in terms of time is that they are effective for the future. For this reason, it is estimated that the allegation of unconstitutionality of the relevant laws will be brought to the Constitutional Court. At this point, it is thought that the Constitutional Court's real-unreal retroactivity jurisprudence, in which it considers retroactive tax laws in a binary distinction, may find application again. In this study, the retroactive consequences of both newly enacted tax laws are determined, the Court's existing jurisprudence on similarly enacted laws on similar grounds is cited, and the consequences of the lack of a change in the Court's jurisprudence are evaluated within the framework of constitutional principles. Finally, it is explained why the Court's realunreal retroactivity jurisprudence should change in the second century of the Republic. In this context, firstly, the preliminary question of which term should be used for retroactive tax laws is discussed. Subsequently, the application of laws in terms of time in tax law is discussed together with the rules and exceptions. In this part of the article, contrary academic opinions and determinations are made by utilizing the doctrine and court decisions. In the following sections of the study, Laws No. 7440 and 7456, which had a primary impact on the writing of the article, are analyzed from various perspectives in terms of their conformity with the Constitution in terms of their norms, including the legislative process. At this point, within the scope of the study, the content of both laws, which are essentially retroactive regulations, has been determined and criticized. In the last part of the study, it is tried to be explained and supported from different angles that the Court's existing jurisprudence on the application of tax laws in terms of time should be differentiated in terms of these two laws. In fact, the fact that both laws contain regulations contrary to the principle of legal security is discussed throughout the study and concluded in the last section. The enactment of retroactive tax laws, which has many examples in the history of Turkish Tax Law, continues to be a reality today. As explained, the current case law of the Court does not include measures to protect fundamental rights and freedoms in the contemporary sense. For this reason, it should be stated that the door is left open to tax laws that may be characterized as retroactive and unpredictable, but which will not be deemed unconstitutional due to the current case law. It can be stated that the Legislature used this open door with the Additional Corporate Tax and Additional Motor Vehicles Tax regulations, respectively. It is considered that the distinction between real and unreal retroactivity developed by the Court should be abandoned in the 2nd century of the Republic since it does not meet the requirements of the principle of legal foreseeability as an extension of the principle of legal security. As a matter of fact, in a state of law where the legal consequences of an individual's transactions and actions should be foreseeable, no one should be deprived of the time and opportunity to re-evaluate and, if necessary, change their actions and transactions according to the differentiating legal consequences. Finally, it would be useful to explicitly regulate the prohibition of retroactivity in terms of tax laws in the Constitution, including in extraordinary periods, even though it is covered by Article 2 of the Constitution. In connection with the right to budget, the relevant regulation could be drafted in such a way that only the tax types included in the relevant budget law (excluding the additional budget) can be pursued and collected in a fiscal year.