As of July 2015, U.S. citizen tourist and business travelers must pay reciprocity fees before arriving in Argentina. People with diplomatic or official passports are exempt from the fee, as are individuals who are in transit and do not enter the country.
To pay the reciprocity fee, an American traveler navigates to Argentina's Provincia Pagos website and pays with a credit card. When entering Argentina, the traveler shows an immigration officer the receipt for payment. The receipt is in effect for 10 years from the payment date and can be used multiple times. The U.S. Department of State recommends making several copies of the receipt, because it is required each time a traveler enters Argentina.