We present theoretical study of spin transport in spin filtering magnetic tunneling junctions, the calculations are based on the Landauer-Büttiker formalism taking into account spin-orbit coupling (SOC). It is shown that spin-flip scattering induced by SOC is stronger in parallel alignment of magnetization of the FB and the FM than that in antiparallel case. The increase of negative tunneling magnetoresistance with bias is in agreement with recent experiment observation.