A two-dimensional Gauss-Kuzmin theorem for N -continued fraction expansions is shown. More precisely, we obtain a Gauss-Kuzmin theorem related to the natural extension of the measure-theoretical dynamical system associated to these expansions. Then, using characteristic properties of the transition operator associated with the random system with complete connections underlying N -continued fractions on the Banach space of complex-valued functions of bounded variation, we derive explicit lower and upper bounds for the convergence rate of the distribution function to its limit.