governmental restrictions on private transactions in foreign exchange (foreign money or claims on foreign money). The chief function of most systems of exchange control is to prevent or redress an adverse balance of payments by limiting foreign-exchange purchases to an amount not in excess of foreign-exchange receipts.

Residents are required to sell foreign exchange coming into their possession to the designated exchange-control authority (usually the central bank or specialized government agency) at rates set by the authority. Some systems permit recipients of exchange from certain sources to sell a portion of such receipts in a free market. Because the control authority thus becomes the only foreign-exchange market, it can determine the purposes for which foreign exchange can be spent and to fix the amount that is available for each purpose.

A controlled exchange rate is usually higher than a free-market rate and has the effect of curbing exports and stimulating imports. By limiting the amount of foreign exchange a resident can purchase, the control authority can limit imports and thus prevent a decline in its total gold reserves and foreign balances.