The idea of a buried oxide layer (BOx) in a split channel Gate All Around-Tunnel Field Effect Transistor (GAA-TFET) was investigated in this paper. This work examined the impact of buried oxide layer on the device's performance. With the BOx layer present and channel length of 20nm, the channel area of the TFET device investigated in this study is divided equally on the same side. The doping concentration has been transferred to the split channel on the drain side. The device’s performance was examined using numerical simulation utilizing simulation software of CAD devices. The final results which incorporate the buried oxide layer were being compared to the uniform split channel GAA-TFET. The parameters like ON current (Ion),OFF current (Ioff), subthreshold swing (SS) and electric-field (E) intensity are observed and compared with silicon (Si) based GAA-TFET and Indium phosphide (InP) based GAA-TFET. It is found that InP based GAA-TFET with buried oxide layer is more advanced device design than the others with Ion and Ioff of 3.02 x 10-05 A/um and 2.09 x 10-22 A/um, respectively.