The vertical excited states of silane are investigated using ten different basis sets to systematically compare the effects of (a) Rydberg functions, (b) diffuse d functions, (c) valence d functions, and (d) a split valence shell. Wavefunctions are generated using all singly excited configurations, excluding inner shells. The low‐lying singlet states are dominated by excitations into the diffuse orbitals, while low‐lying triplets have significant valence character. Valence d functions have a minor effect on excitation energies if an adequate valence s p basis set is used. The main effect of Rydbergd functions is to introduce additional Rydberg states below the first ionization potential and above the s and pRydberg levels.