Upon arrival in Mexico you will need to have a valide passport and fill out a visitor’s permit known as the FMM (Forma Migratoria Multiple). This form is provided free of charge by your travel agent or airline, or at point of entry in Mexico.
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Apart from passport and Visa, the immigration officer at passport control also may ask you to prove the necessary economic means and a return ticket to your country.
Immigration will check your documents and stamp and process the FMM form, return back the right-hand portion, which you must hand in when you leave Mexico. NOTE: If you lose this form, you will have to go to the immigration desk at the airport and may have to pay a fine, so better take care of it! Customs Procedures at any international arrival airport (like Morelia, Guadalajara, and Mexico City)
During the inbound flight, you will also receive a customs form (Hacienda) which indicates all items that are not allowed or limited in quantity to be imported. This form may be available in English, Spanish, French or Japanese, according to your flight. If you exceed the allowed quantities, you may pay the corresponding import duties (around 20% but limited to a maximum declared value of US$3000; you may need to proof the value with invoices). After passing through immigration, you collect your bags and proceed to the exit. You will hand over the customs form to the customs official and press the button on what looks like a traffic light. A green light means “go” and a red light means “inspection,” in which case a female official performs a quick inspection. There is no yellow light, by the way.
You are not allowed to bring food, fruits, and/or products that are not “company” packed and sealed. And if you are bringing food or products, they are allowed only if you need them because of a special diet or for medical reasons. The same rule applies to medicine. You are allowed to bring enough medicine for the time period you will be in Mexico. If you are bringing an unusual quantity of medicine, you will need to bring a doctor’s prescription just in case you need to prove the medicine is for your own consumption. Read responses to frequently asked questions here.
If you have a connecting flight to any other Mexican airport, you will have to go through the above procedure and after the customs inspection you will have to check-in your luggage. Depending on the airport, this may be directly leaving the customs area or not.