Definition of junior or under age is made at some laws such as Civil Law and Criminal Law in Turkey. Also, conditions of majority are treated at some laws. Besides, it is indicated that tax responsible who fulfills the tax obligation is legal representative as guardian, custodian, and administration in Civil Law. Explaining concepts of under age and disabled is importance in terms of person who pays original tax and person on which imposed a tax penalty. For this reason, in this study, the legal status of the under age and disabled persons and their legal representatives, who are deemed to be tax responsible, in terms of paying original tax and tax penalty are discussed.