Millennium Challenge Corporation Eligibility Expansion Act This bill modifies income-related eligibility requirements for assistance from the Millennium Challenge Corporation (MCC), a program that provides assistance through a competitive selection process to eligible developing countries based on various factors, including a country's level of economic freedom and effectiveness of government. Currently, to be a candidate to receive MCC assistance, a country must, among other requirements, must (1) fit the World Bank's income-based criteria for a low- or lower-middle-income country, or (2) be among the 75 lowest per capita income countries according to the World Bank. Under this bill, a candidate country must have a gross national income per capita no higher than the 125th poorest country as identified by the World Bank for the fiscal year.