Customer Retention Cost is an indicator we use to calculate the costs associated with retaining an existing consumer. The calculated data gives us an overview of the market situation or problems with the marketing plan. Analysis of the results can also contribute to acquiring more customers and reducing the number of their departures, as well as increasing the spending of existing consumers. Unfortunately, calculating retention costs does not have a universally accepted formula and is a complex process that can include various aspects, e.g. the cost of training, marketing, adapting a new function.