The article presents the development of certain methodological fundamentals of financial outsourcing (F & O) in modern conditions. Analysis of the F & O practice has demonstrated that financial outsourcing, which is widely used in the developed countries as a modern tool for managing finances of economic entities, has not found wide use in Russia. For increasing its use in the Russian economy, a basic F & O conception as a direction in theory of managing the finances of economic entities has been developed. The author proposes a solution of certain problems related to the development of an organizational management mechanism.