Based on the experimental calculations carried out with the help of the shifting mode reproduction model, as well as on the theoretical studies of Marx, Schumpeter, Keynes and his followers - representatives of the post-Keynesian direction, two conclusions were made in the article. First, that non-neutrality of money takes place in both short- and long-term periods, and second, that each of these periods has its own basic preconditions for non-neutrality. For the short term, it is a "phenomenon of nominal rigidity", and for the long term, it is a "phenomenon of capitalization of money". The thesis is justified that the "phenomenon of nominal rigidity" manifests itself mainly within the framework of the existing production, when the economic growth caused by the increase in money supply is achieved by increasing capacity utilization and engagement of idle labor. Accordingly, the "phenomenon of capitalization of money" manifests itself through the conversion of issued money into investments in fixed capital and, through the growth of this capital (and capacities), affects the GDP growth. It is shown that behind the two considered basic prerequisites there are fundamentally different theoretical approaches. Behind the short-term "phenomenon of nominal rigidity" there is an orthodox vision of economy focused on the equilibrium pricing mechanism. Behind the long-term "phenomenon of capitalization of money" there is a heterodox vision related to the mechanism of money circulation, emission and economic growth caused by it. It has been concluded that in case of probable increase of competition between these theoretical approaches it is unacceptable if short-term basic preconditions of non-neutrality of money are used in the analysis of long-term processes and long-term preconditions are used in the analysis of short-term growth cases.