The article is devoted to the study of the ideas of the famous statesman and public figure of the XIX century M.M. Speransky. His merits in the development of legal science and legal education in Russia are noted, as well as his achievements in the field of financial law are especially emphasized. The project of financial reforms prepared by M.M. Speransky, called the “Finance Plan”, is analysed. The economic situation that caused the financial transformations is considered, and the measures proposed by the great Russian reformer in the field of budget revenues and budget expenditures are examined in detail. The authors note the significant contribution of his idea to the formation of the principles of the budget system of Russia – the principle of budget balance, the principle of efficiency in the use of budget funds, the principles of budget independence and the delimitation of revenues, expenses and sources of financing budget deficits between the budgets of the budget system of the Russian Federation. The classification of budget expenditures proposed by M.M. Speransky for necessary, useful, excessive and excessive (useless) helps to reduce government costs and is very relevant for modern Russia. However, for its legislative consolidation, a clear system of criteria is required. It is also proposed to implement this idea by establishing the category of “priority expenses”, referring to them the so-called necessary expenses to be implemented in any state of affairs. The article indicates significant attention in the works of M.M. Speransky to the issues of proper order and the correct, transparent organization of a particular activity. It is also emphasized the relevance for the modern economy of Russia of its ideas on the reform of budget revenues, their unification, the consolidation of the principle of certainty of taxation and fees. The authors conclude that it is possible to further reform Russian financial legislation through the development of the ideas of M.M. Speransky.