Rare-earth borohydrides have recently attracted a strong interest as potential hydrogen storage materials. While the local structure of the BH4 − ion can be probed using vibrational spectroscopy, the local structure of the rare-earth ion can be studied using luminescence spectroscopy. This is reported here for Tb(BH4)3 and its solvate with S(CH3)2. The spectra clearly show smaller CF splittings for the unsolvated compound. These experimental data are compared with recent DFT+U calculations of the energy levels and CF splittings for Tb(BH4)3 and show that these calculations significantly overestimate the experimental results.