Actinide intermetallic compounds continue to attract considerable interest due to the coexistence of localized and itinerant 5f electronic behavior and the resulting rich electronic and magnetic phenomena. Here, we investigate the electronic structures, magnetic properties, and anisotropic thermoelectric responses of layered AnCo4Al8Si2 (An = Th, U, Np) using density functional theory calculations including spin-orbit coupling and Hubbard U corrections. While Th is nonmagnetic and weakly affected by electronic correlation, the U and Np compounds exhibit pronounced correlation-dependent magnetic behavior associated with partially filled 5f states. The calculated electronic structures reveal that metallic transport is governed primarily by Co d bands, whereas the actinide 5f states modify the low-energy electronic structure through hybridization effects. In particular, the Seebeck response evolves systematically across the series, and the Np compound exhibits opposite signs between the in-plane and out-of-plane Seebeck coefficients. These results demonstrate that f -electron occupation provides a tuning parameter for anisotropic thermoelectric behavior in layered actinide intermetallics.