Departure Requirements for Costa Rica
Departure or Exit Tax
The departure tax for Costa Rica is not included in airline tickets and must be paid in cash (U.S. dollars or Costa Rican Colones) or by credit card before you check in at the airline counter for your flight. The tax is $28 per person (it increased in 2011 from $26).
You will not be allowed to check in without first paying this tax, and because of the way the tax works (see below) you may not be allowed to check in at all if you have not reached the counter at least one hour prior to your scheduled departure.
The departure tax is used for a variety of public projects including road improvements and marketing campaigns to try to attract more visitors to pay the departure tax...
Paying the Tax in Advance
You may pay your departure tax in advance by presenting your passport at participating hotel and resort's front desk. Generally the hotels will charge you a service fee of $2 to $10 per person and accept the same methods of payment as at the airports. You may also pay your departure tax in advance at any Bank of Costa Rica but this can be a tedious process.
Why isn't this Included in the Airfare Like Everywhere Else in the World?
Collecting this tax from you in person is unusual. Typically all the taxes and fees you have to pay are included in the price you pay for your airline ticket, but Costa Rica and a couple of other countries prohibit the airlines from including the tax.
One of the reasons for collecting the tax in person is that between the time you pay the tax and the time you board your plane immigration is using the information you provide to check up on you and make sure there is not an "impedimento de salida" (legal restraining order prohibiting you from leaving) issued in your name or any other reason (unpaid speeding tickets etc.) to prevent you from leaving.
Because they need time to check this data you may not be allowed to check in for your flight if you are not at the counter more than one hour in advance. In the past they commonly overlooked this rule, but now they are sporadically enforcing both this regulation and the regulations pertaining to entering the country to the letter of the law.