For that purpose, we will start with a very simple model. The idea is as follows. Suppose the immigrant weights in each period the benefits of remaining a further unit of time abroad against the costs of doing so. He/she will then decide to return home when the benefits of staying abroad are lower than the cost. When does this situation occur? The most important reason for emigration are higher wages in the host economy. This creates additional wealth, and allows the migrant to increase lifetime consumption. However, as the marginal utility of wealth decreases, the additional benefit of a unit of time in the host country is the lower, the longer the migrant has already stayed abroad (and the more wealth he/she has accumulated). Accordingly, the benefit of migration slowly decreases. This alone does not trigger a return migration, since, whatever the immigrant’s wealth, it is always advantageous to remain a further unit in a country that pays a higher wage.