The phenomenon of demographic bonus is one of the opportunities to increase tax revenues since the increase in productive age population will be inversely proportional to the increase in the number of taxpayers in the future. The problem facing the government is still the same, the lack of tax compliance and tax awareness among the taxpayers. One of the services in the field of taxation which is provided by the government, the Directorate General of Taxes, is the online based facility to report taxes through an e-filing system. However, it seems that many millennials, as the successors of the nation’s next-generation, do not utilize the e-filing system well. The current study sought  to examine the acceptance process of e-filing technology among the millennials. This study used a quantitative approach with a questionnaire as the research instrument. The population of the study was people who were in the age of millennials, namely those who were between 20 and 40 years old in 2021. The results show that the factors of innovativeness of the millennials are a crucial factor that suggests that e-filing is not difficult to be implemented. Nevertheless, the findings also revealed that there is a risk factor that prevents them from using e-filing. It cannot be denied that millennials may technically not find any problems with the systems implemented. Although the current study showed the implementation of the TAM theory in e-filing issues, there are some limitations. The current study did not show whether there is a difference between the millennials’ behaviour of the acceptance of e-filing and their high or low incomes or their lifestyle.