Foreign film crew is required to have a work permit/visa. This is called an FM3 and is valid for six months (renewable thereafter). You can get an FM3 for a year, but it may take longer (and require the assistance of your Mexican attorney) to obtain.
Once you agreed to work with a Mexican film union the easiest method of obtaining work permits for your cast, crew and staff is to procure the necessary backup documentation for each person you are bringing to México, and turn that information over to your Mexican production manager, production coordinator or attorney, who can complete the process and procure the permits. The process is relatively straightforward. Compile the following package of documentation for each individual who needs a work permit:
a) A completed Work Permit Information Form.
b) A valid passport.
c) A letter from the company (on company letterhead) explaining why this person is needed to work in México.
d) A completed and signed Application for Mexican Visa.
e) Four (4) passport photos -- two front and two right profile shots.
f) Work permit fee (about) 200.00 US.
We recommend a separate envelope with documentation for each person with their name on the outside. Submit groups of envelopes as they are ready, and prepare an additional letter authorizing a person (whomever is procuring work permits for your production) to represent the employees applying for Mexican work visas. Although each person is supposed to apply for their own work visa, Work Permit Application Forms are often submitted by someone applying on behalf of other individuals. Employees may be reluctant to give up their passports, even for a short period of time; but their work permit cannot be obtained without it.
Once the production manager, coordinator or attorney has complete packages, he or she will secure authorization for entry into the country from the Mexican National Institute of Immigration in México City. The authorization along with all of the other documentation is then submitted to Immigration in Rosarito or Tijuana or to a Mexican Consulate in the U.S., where the work visas are issued within 1-3 working days. It is usually allowed for a worker to enter México after an application has been submitted. If ou choose to submit the entry letters and backup documentation to the Mexican Consulate on your own, be advised that some consulate offices will allow you to apply for other individuals and some will require that each person apply in person. The work permit process should not take long, but begin as early as possible just in case there are hold-ups along the way.