Abstract Density functional theory and generalized gradient approximation including a Hubbard-like term were used in the present investigation of tetragonal barium titanate crystal codoped with Ni and Fe impurities. Ubiquitous in any oxide material oxygen vacancy defect has been considered as well. Atomic shifts from their positions in pure crystal state as well as electronic and magnetic features are studied and described in the present work. Based on the density of states patterns we also provide insight into electrical conductivity of BaTiO 3 for different cases.