AbstractUsing a simplified parabolic band model approach within the framework of the envelope function approximation, the influence of in‐plane magnetic fields on the electronic and optical properties of type‐I superlattices is studied. The results are in qualitative agreement with experimental facts previously reported, as well as with previous theoretical results obtained using more elaborated and toilsome methods. Furthermore, this approach allows to advance, in a great extent, in the analytical treatment of interband transitions, leading straightforwardly to some general conclusions. The not well understood case of high magnetic field effects (magnetic length comparable with the superlattice period) is studied in detail. There strong variations of the interband transition strengths as function of the cyclotron orbit center position are found, a fact which is directly connected with the broadening and final saturation of the magneto‐absorption spectrum with increasing fields. A consistent explanation of such strong variations is given in terms of magnetic subband mixing.