This paper considers a system of two mathematical models for constructing an average tax rates scale. The first model with six specified numerical parameters is intended for constructing the average tax rates scale and represents a certain variational game-theoretic model. The second — approximating one — is meant for constructing a marginal tax rates schedule based on the optimal average tax rates scale. It is a problem of the best approximation to the optimal average tax rates schedule by average tax rates scales, and it can be presented in a tabular form traditional for economy.