With the advent of electric power systems moving from a vertically integrated structure to a deregulated environment, calculating reactive power service charges has become a new and challenging theme for market operators. This paper examines various methods for reactive power management adopted throughout various deregulated foreign and domestic markets and then proposes an innovative method to calculate reactive power service charges using a reactive power market in a wholesale electricity market. The reactive power market is operated based on bids from the generating sources and it settles on uniform prices by running the reactive OPF programs of the day-ahead electricity market. The proposed method takes into account recovering not only the costs of installed capacity but also the lost opportunity costs incurred by reducing active power output to increase reactive power production. Based on the result of the reactive OPF program, the generators that produce reactive power within the obligatory range do not make payments whereas the generators producing reactive power beyond the obligatory range receive compensation by the price determined in the market. A numerical sample study is carried out to illustrate the processes and appropriateness of the proposed method.