The research aims to examine the ability of the cost of digital tax reform to control the performance of public finances in Egypt. To achieve this aim, the researcher used the multiple regression method to analyze the ability of the cost of digital projects implemented in various tax departments in Egypt to explain the level of public finance performance during the first five years of adopting the digital tax reform approach (2014/2015 -2019/2018). The researcher relied on five indicators for the performance of public finance are: the public revenue ratio, the public expenses ratio, the total deficit ratio, the cash deficit ratio, and the primary deficit ratio. The researcher reached several results, the most important of which are: There is a significant effect of the cost of digital tax reform on all public finance performance indicators, except for the public expenses ratio. And that this effect was negative for the percentage of public revenues, and positive for the rest of the indicators.The researcher recommended the necessity of paying attention to the cost of the digital tax reform as one of the explanatory factors for the performance of public finances in Egypt, and that containing the public budget deficit of all kinds requires taking into account the costs of the project of customs port buildings, the costs of the real estate tax collection devices project, the costs of the government spending mechanization project, The costs of the information technology project in the Minister"s office sector, the costs of the value-added tax collection devices project.