Les contraintes de liquidité dans la théorie du cycle de vie

The Life Cycle Model implies an excessive indebtedness if borrowing is permitted at a rate equal to the lending rate. This will induce at the macroeconomic level a negative asset position for the whole household sector. Two extensions of the model will be described here, the consumer faces quantity constraints on the amount of borrowing, and the borrowing rate is higher than the lending rate. We are concerned with the solution of these optimization problems in a general framework. The imperfect capital market implies an important modification of the usual results of the basic LCH, namely the existence of time interval where consumption is determined by current income instead of permanent income. A numerical solution, with observed wages profiles, allows us to appreciate the efficiency of our regulation types, and we see that the existence of a spread corresponding to the observed data generates reasonable limits on borrowing and makes the quantity rationing unnecessary.