The article systematically investigates the legal bases of planning and formation of the defense budget of Ukraine. It is stated that the legal bases of the defense budget of Ukraine are the Constitution of Ukraine, the Budget Code of Ukraine, the Law of Ukraine «On National Security of Ukraine», the Strategic Defense Bulletin of Ukraine, the National Security Strategy, the Military Doctrine of Ukraine, the laws of Ukraine on the state budget for the respective year. It is stated that at the legislative level the sources of financing of defense expenditures are fixed: funds of the state budget of Ukraine, charitable donations, income from own economic activity of the Armed Forces of Ukraine. The mechanism and conditions for providing charitable assistance to the Armed Forces of Ukraine are described. The expediency of revising the Concept of economic and economic activity of the Armed Forces of Ukraine approved on April 19, 1997, approved by the President. The current Concept does not meet current conditions. It needs revision, based on Ukraine’s NATO course, of military aggression, reformatting the structure of the Armed Forces of Ukraine. It has been determined that the amount of defense expenditures as a percentage of the gross domestic product meets international standards. However, the weakness of the national economy indicates a lack of defense spending in dollar terms and in terms of one soldier. The expediency of optimizing the structure of expenditures, reorientation of creation of new administrative and economic units for project management in the sphere of defense, creation of an effective mechanism of public control over the distribution of defense expenditures is argued. Keywords: defense budget, legal framework, gross domestic product, national security, defense, budget, charitable donation, economic activity.