Devaluation of currency may not correct a balance of payments deficit if the demand for export is

Perfectly inelastic. If the demand for a country's exports is perfectly inelastic, it means that the quantity demanded of those exports does not change, no matter what the price is. In other words, the price of the exports does not affect the amount that people are willing to buy. In this case, devaluing the currency (making exports cheaper for foreign buyers) will not lead to an increase in demand for exports and thus will not correct a balance of payments deficit. The demand for the country's exports would have to be fairly elastic or perfectly elastic for devaluation to have an impact on the balance of payments.