The Eurocode EN 1990  Annex B Clause B.3 allows a risk oriented differentiation of the reliability levels with the definition of different consequences classes CC1 to CC3. This can occur through decrease or increase of the safety factor for either the action or the resistance. Should the reliability level of an individual structural component or individual structural check need to be differentiated, it is appropriate to consider the resistance side. If the whole structure is to be assigned a certain consequences class, or if the reliability level relates to a particular action, it is appropriate to consider the action side. In any case the inclusion in an independent factor KFI provides more transparency. The partial factors can then remain unchanged. This article describes the background and derivation of these force importance factors. © Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.