All U.S. citizens must present a valid U.S. passport to enter and exit Colombia, and to enter the United States. Dual U.S-Colombian citizens must present a Colombian passport to enter and exit Colombia, and must have a U.S. passport to return to the United States. U.S. citizens do not need a Colombian visa for a tourist stay of 60 days or less.
Tourists entering Colombia may be asked for evidence of return or onward travel, usually in the form of a round-trip ticket. The length of stay granted to travelers will be determined by the Colombian immigration officer at the point of entry and will be stamped in your passport. Any additional extensions may be requested at an office of the Colombian immigration authority, known as DAS (Departamento Administrativo de Seguridad) Extranjeria, after arriving in Colombia. Fines are levied, if a traveler remains in Colombia longer than authorized. Any foreigner who possesses a Colombian visa, valid for more than three months, must register the visa at an office of DAS Extranjeria within 15 days of arrival in Colombia, or face fines.
There is no arrival tax collected upon entry into Colombia, but travelers leaving by plane must pay an exit tax at the airport. Some airlines include a portion of this tax in the cost of your airline ticket. Check with your airline to find out how much of the tax you will have to pay at the airport.