Technetium-99 (Tc) displays a rich chemistry due to its wide range of accessible oxidation states (from -I to +VII) and ability to form coordination compounds. Determination of Tc speciation in complex mixtures is a major challenge, and Tc-99 nuclear magnetic resonance (NMR) spectroscopy is widely used to probe chemical environments of Tc in odd oxidation states. However, interpretation of Tc-99 NMR data is hindered by the lack of reference compounds. Density functional theory (DFT) calculations can help to fill this gap, but to date few computational studies have focused on Tc-99 NMR of compounds and complexes. This work evaluates the effectiveness of both pure generalized gradient approximation and their corresponding hybrid functionals, both with and without the inclusion of scalar relativistic effects, to model the Tc-99 NMR spectra of Tc(I) carbonyl compounds. With the exception of BLYP, which performed exceptionally well overall, hybrid functionals with inclusion of scalar relativistic effects are found to be necessary to accurately calculate Tc-99 NMR spectra. The computational method developed was used to tentatively assign an experimentally observed Tc-99 NMR peak at -1204 ppm to fac-Tc(CO)(3)(OH)(3)(2-). This study examines the effectiveness of DFT computations for interpretation of the Tc-99 NMR spectra of Tc(I) coordination compounds in high salt alkaline solutions.