The aim of this study is to show a brief analysis on credit sales for future services to protect the financial stability of businesses that offer them. An introductory review on the existing demand of future services is done, some theoretical basis on the concepts of savings funds, investment funds and future services are analyzed in order to understand their differences. Finally, a formula to estimate costs for future services is proposed in order to obtain the approximate costs of the services they are selling today to the moment when they are required in a future date and to make this profitable by using a financial scheme based on ordinary annuities.