We analyze the role of the energy flow coefficient in beam shifts and develop the theory of the angle spectrum method to calculate the beam shifts of polarized beam reflection and transmission. By applying the self-consistency between the law of conservation of momentum and the angular Goos-Hänchen (GH) shift, we prove the necessity of the correcting energy flow coefficient of the transmitted light fields. For the air-glass interface, we find that the influence of the energy flow coefficient on the angular GH shift is very pronounced in the case of close grazing.