Global remittances are forecast to decline by about 20% this year as the economic crisis caused by the coronavirus pandemic shuts down business activity, the World Bank says.
This is the sharpest decline on record for what has become a lifeline for many people in Africa and elsewhere.
Migrant workers will not send as much money home because their employment and pay is vulnerable.
Globally money sent home by workers abroad to low and middle-income countries is forecast to fall by about $445bn (£360bn).
The decline for sub-Saharan Africa is predicted to be 23% and amount to $37bn this year.
The World Bank report also highlights how the cost of sending money to the region is about a third more expensive than the global average.
The average commission charged for sending $200 is 9%, but for southern Africa it can cost as much as 20%.