The intraatomic Coulomb repulsion of itinerant electrons provides another Stoner mechanism of band splitting leading to ferromagnetism. The behavior of the magnetization versus external magnetic field is derived by an approximate treatment of the local correlations in a simple mean-field approximation for 1D, 2D, and 3D cubic lattices. The criteria for first-order phase transition and full spin alignment in an applied magnetic field are found. These attempts should be regarded as a way to obtain an upper bound for the magnetic moments. The appearance of ferromagnetism is seen for larger values of the intraatomic interaction U and lattice parameter a. This study provides a better understanding of the mechanism of strong ferromagnetic saturation and may help explain the behavior of magnetic moments of certain Fe sites in Fe-N compounds.