Most airlines do not let you check-in online if you need a visa to travel to the destination country. If you check-in online or at the airport, either way, make sure to arrive at the gate a bit early and see the airline staff. They sometimes have to go through the visa requirements again, verify the documents and put a “Docs Ok” stamp on your boarding pass.
Passport must be valid for at least 6 months from the day of travel.
You must fill a Forma Migratoria Múltiple (FMM) card before you enter Immigration and Customs at your port of entry. Normally, an FMM card will be given to you on your inbound flight.
At your first port of entry in Mexico, you have to go through the Customs and Immigration. You will be asked about your purpose of travel, whether it’s your first time in Mexico, etc. Your passport will be stamped. The number of days you will be allowed to stay will be marked on the FMM card. Usually, it would be 180 days.
You must retain the FMM card while you are in Mexico. If you lose, you have to pay a penalty on your exit.
As always, carry a copy of your return ticket and hotel/hostel/Airbnb booking for just in case.
You have to return the FMM card to the airline staff on your exit. If you lose your FMM card, you must pay a penalty. To avoid any penalties and delays on your exit, make sure to keep the FMM card safe while you are in the country.
As usual, stop by the gate to check with the staff if they need to verify your documents.
You may have to go through immigration and customs on your return at your home country or the country you are flying back to. If you are flying back on an Airbus A330/A340/A380 or Boeing 747/777, expect long lines at the immigration and customs.