To better account for approximate QP excitation effects, we adopt the successful generalization of the DFT-1 /2 method to the DFT+A-1 /2 scheme, extending it from conventional semiconductors to insulating compounds with shallow d-levels. To determine the critical parameters of the scheme, the amplitude A and the self-energy potential V S , we conduct a detailed study of the fundamental gaps and d-level positions of the equilibrium phases β-Ga 2 O 3 and δ-In 2 O 3 in more detail. Encouraged by the success of the method for monoxides such as ZnO and CdO, we apply the same two-step procedure to determine A and V S .