From a Moving to Mexico Facebook group post by Beto Rodriguez · 

I get the frustration. Mexico can feel overwhelming when you suddenly have an INE, CURP, RFC, passport number, immigration documents, and a folder full of paperwork.

But here’s the thing: those numbers are not duplicates. They belong to different systems.

Your passport is your international travel document.
Your CURP is your population/civil ID in Mexico.
Your RFC is your tax ID.
Your INE elector number belongs to your national voter/identity credential.

The real issue isn’t that Mexico has no logic. The issue is that the systems are not always unified in a user-friendly way.

A few useful tips for foreigners living in Mexico:

 Keep digital and printed copies of all your documents.
 Save your CURP, RFC, INE, passport, and residency card in one secure folder.
 Make sure your name matches exactly on every document.
 Do not wait until the last minute to fix government paperwork.
 When possible, ask which specific number they need before giving every document.
 Remember: SAT = taxes, INE = ID/voting, CURP = civil identity, Passport = travel.

Mexico can be bureaucratic, yes. But once you understand what each document is for, it becomes a lot easier to navigate.