The linearised DC loadflow is a fast way to calculate the load flow. However, until now changes in topology due to busbar splitting cannot be dealt with in an efficient way. In this study, we introduce the Bus Split Distribution Factors (BSDF) which enable an efficient way to compute the effects of busbar splitting on the DC load flow. The derivation of the BSDF formulas is based on modelling the busbar coupler as a branch with vanishing reactance and by using transformed LODF formulas. In times of the energy transition the BSDF approch might be especially helpful since optimal grid topology control is still a largely unexploited form of flexibility for system operators due to the complex combinatorial nature of grid topology reconfiguration. With the BSDF approach much faster screening of topological remedial actions (including substation reconfigurations) in congestion management applications is possible.