Donald J. Trump has finally provided some details on how he plans to make Mexico pay for his proposed border wall. Unless the Mexican government pays $5 billion to $10 billion to build it, he wants to restrict the money, or remittances, that Mexican immigrants send back to family and friends in Mexico.

There are a number of logistical problems with this plan, including political realities, legality and the feasibility of stemming the flow of these informal payments. But even assuming this policy was possible, the economic implications would be felt as much in the United States as in Mexico.

While my research suggests that Mexican immigrants in the United States may initially have more disposable income if they could not send money, their families back home would be less likely to invest in education, start businesses and get out of poverty. This could damage Mexico’s economy: Mexico receives $24.4 billion in remittances from immigrants in the United States, which accounts for about 2 percent of Mexico’s gross domestic product. Indeed, withholding this money may actually encourage immigration to the United States.