The Spendthrift Economy
This assumes a circular flow of income in a closed economy with no Government sector and no foreign trade. It also assumes the existence of two sectors, namely the sector of households and the sector of firms. Firms make the commodities that households consume. They purchase the services of factors of production from the household that own them, paying wages, rent, interest and profits in return, and then use the factors to make commodities.
It is assumed firms sell all of their output to households and receive money in return. All of the money received is in turn paid out to households. Part goes to households that sell factor services to firms, and the rest is profit paid out as Dividends to the owners of the firm. In short, neither households nor firms save anything in the spendthrift economy; everything that one group receives goes to buy goods and services from the other group. Expenditure is the rule of the day!
Now, suppose we wish to calculate the Total Value of the economy's output. We can do this based on either side of the circular flow shown in the figure above. The output-expenditure approach uses calculations based on the flows on the right hand side of the figure, while the input-factor income approach uses calculations based on the flows on the left-hand side of the figure.