There is an increasing need in the electric utility industry to replace the conventional methods by using advanced approaches for improving the existing performance of various tools. This paper presents the results of electric distribution system Interrupted Energy Assessment Rate (IEAR) evaluation by a new computation approach based on Multilevel Monte Carlo simulation coupled with Milstein discretisation scheme. The aim of the proposed approach is to speed up the simulation of IEAR estimation. For validation, applications of the proposed method are implemented to some distribution systems. The output results are compared with those obtained from time-consuming basic sequential Monte Carlo simulation. The effects of the constant and time-varying load and cost models on the computation performance are determined.