Following criticism of ideas emerged from the theoretical debate among schools of thought over the possible effects of Public Deficits, this work introduces the most realistic and best-theorized Consumption Expenditure Function development ever. The Consumption Expenditure Function formulation that comes out of a new mathematical development will include a subjective and an objective part when referring to consumption expenditure decisions. From now on, economists will only pay attention to how consumption expenditure behaves in front of changes that affect these objective and subjective parts. Microeconomic theorists have always talked about the existence of utility indifference curves when referring to consumption expenditure decisions but every theoretical development lacks this revealing concept. Part of this work deals with a thorough analysis of this issue and presents, for the first time and to the entire international academic community, a mathematical development that will allow, from now on, to take indifference curves into consideration within every old and new economic model.