"...........All foreign residents in Mexico will soon be required to have a tax number due to a recent tax reform. Temporary and permanent residents aged 18 or over or anyone with a CURP identity number must have an RFC number by July 1 whether they earn income in Mexico or not..........." For more info see Mexico News Daily  on line.  My opinion is this will be totally impossible to do for everyone by July 1 because all Mexicans over 18 must also register, and they can only do so many