Upward lightning is the dominant type of lightning discharge to tall structures. It has been observed that a significant number of these upward flashes are initiated by nearby lightning activity. The aim of this study is to estimate the incidence of upward lightning flashes from tall structures caused by nearby lightning based on Monte Carlo simulations and using a simplified electrostatic and corona model. We present the spatial distribution of different nearby lightning events that can potentially trigger upward lightning from a given structure. Our results suggest that Eriksson’s empirical formulas might significantly underestimate the total number of flashes to a tall structure.