In conditions of macroeconomic instability characterized by increasing inflation and slowing growth or a decrease in gross domestic product (GDP), one of the main directions of government countercyclical regulation, along with monetary policy, is fiscal policy. However, if the existence of a bidirectional relationship between an increase in government spending and an inflation growth seems empirically justified in the context of the implementation of difficult-to-predict risk events, then determining the existence and nature of this relationship over a long period of time, including at various segments of the economic cycle, is a debatable issue of economic science and practice. In order to increase the efficiency of budget planning and minimize the possible inflationary consequences of a government spending growth, it becomes urgent to solve the problem of identifying, analyzing and modeling the dependence of inflation indicators on government spending in Russia. In the course of the study, theoretical concepts that reveal the nature and degree of this dependence are considered. The possibility of a multidirectional impact of changes in government spending on inflation, depending on the effect on aggregate demand and aggregate supply, the type of expenditure, the simultaneous impact of monetary policy measures, the characteristics of the national economy and macroeconomic factors, the methodology of the study, is revealed. The economic and mathematical model developed as a result of the study allows us to draw empirical conclusions about the presence of a weak and predominantly direct nonlinear dependence of inflation indicators on the dynamics of cash execution of public expenditures (with a lag of up to 10 months), which does not contradict the assumption of the dominant role of the channel of influence of changes in the volume of public expenditures on aggregate demand in the market of goods and services in the conditions of the Russian economy with a high share of payments to individuals in the structure of government spending.