Electric currents in the solar corona provide the energy for solar flares. However, the determination of coronal currents depends on coronal magnetic field models constructed from vector magnetic field values determined for the low solar atmosphere, and there is considerable uncertainty in the results. We discuss existing approaches to modelling, and how the currents in the models can be validated. We discuss also the Gauss separation method (Schuck et al. 2022) which may be used to identify the components of the field in the boundary due to the currents in the corona. This technique can in principle be used to improve the models, and hence better determine the coronal currents.