LaxBa1-xSnO3 is a promising transparent conducting oxide whose high mobility facilitates potential applications in transparent electronics, oxide electronics, and power electronics. Here, we report quantitative comparisons between angle-resolved photoemission and density functional theory, demonstrating a close agreement between calculations and the measured bulk electronic structure. Further measurements reveal upward band bending at the film-vacuum interface, while ultraviolet (UV) exposure is found to increase the surface electron density, similar to other oxides. These results elucidate the LaxBa1-xSnO3 (LBSO) interfacial electronic structure and offer a route for UV carrier density control, critical steps towards realizing LBSO-based electronic devices. © 2018 Author(s).