The largest problem that we encounter when creating a numerical model of a hard coal deposit is to insert discontinuity lines representing faults, seams junction lines, wedging, etc. The faults introduced on the map of the seam are mostly flat polylines, while we do not know the altitude ordinate. In order to determine the spatial position of the faults, authoring methods have been developed and implemented in the Geolisp software and in the CAD system. This article presents the method based on calculating the spatial position of the fault with respect to the existing contours, which arrive at it from both sides, the method based on the assumption that the inclination of the seam in front of and behind the fault is constant, the procedure involving the performing of independent surfaces of the upthrow and downthrow side with extrapolation by the Kriging method, and the procedure requiring the transfer of the fault from the above-lying seam or a Carboniferous roof. The solutions given in the article are successfully used in most mines in Poland. The correct introduction of the fault course is important for the accuracy of forecasting the impact of the mining operations on the rock mass and the surface area.