Applicants wishing to  work in Mexico, the employment petition must be filed  by a Mexican corporation or  independent (personal)  business, prior arriving Mexico.  If applicant already has a Temporary Green Card obtained through personal income,  or marriage he/she can apply for  change of status to working. 

1. For how long is the working green card valid.  1 year after that can be renew for 1,  2 or 3 years at once.
2. Can I work for different companies with the same green card. No
3. How much is the working green card.  About $250.00, US first year
4.  How long is the process to obtain a Working Green Card. About 2 to 3  months. 

 Temporary Mexico Green Card holders who obtained their resident status through income or marriage can open their own business in Mexico, if they want to be self-employed.  Temporary Mexico Residency Status allow applicants  to register a business at SAT, then apply for work permit. The temporary resident card will be the same except will have an indication stating PERMISO PARA TRABAJAR, which translates (permit to work). The  working permit fees are about $173.00, U.S.