To investigate the first point, we rederive the general expression of the paramagnetic shielding using a sum-over-states formulation (eq. 8) . Following this, we apply a series of approximations in order to recover the equation of the three approaches. We then compare the computed shifts from these three model equations with experimental data from two hexacoordinated Co 2+ complexes, namely the [Co(AcPyOx) 3 (BPh)] + and CoTp 2 complexes (see Fig. ). The Co 2+ ion was chosen because it exhibits significant SOC (ζ =400-450 cm -1 ) , which introduces significant first-order orbital contributions to magnetic properties and a lanthanide-like electronic structure of a ground pseudo J manifold with multiple thermally populated excited states. However in contrast to lanthanide ions, the regular DFT methods still manage to account for the contact hyperfine contributions from Co 2+ without the need of fractional occupation calculation due to large ligand field splitting of the 3d orbitals. The experimental 1 H and 13 C NMR chemical shifts of the CoTp 2 complex were taken from Refs. and for the [Co(AcPyOx) 3 (BPh)] + complex from Pavlov et al. .