  We discuss a family of models expressed by nonlinear differential equation
systems describing closed market societies in the presence of taxation and
redistribution. We focus in particular on three example models obtained in
correspondence to different parameter choices. We analyse the influence of the
various choices on the long time shape of the income distribution. Several
simulations suggest that behavioral heterogeneity among the individuals plays a
definite role in the formation of fat tails of the asymptotic stationary
distributions. This is in agreement with results found with different
approaches and techniques. We also show that an excellent fit for the
computational outputs of our models is provided by the k-generalized
distribution introduced by G. Kaniadakis (Physica A 296 (2001) 405-425).
