RFC used to be required before by Amazon Mexico. But recently, due to tax enforcement, FBA sellers on in Mexico is required to submit CSF (Constancia de Situacion), in addition to RFC. Only companies registered can have CSF. Apparently, most international FBA sellers can not have it, and it is not practical to require FBA sellers to make registration in Mexico.
It looks like mission impossible. Description on Amazon Mexico is totally lawyer's language, hard to interpret.
Figure 1. Imports to Mexico and RFC number
However, the purpose of CSF is to collect sales tax so that Mexico government has additional source of income. Therefore, RFC is not mandatory any more, as long as sales tax can be collected and be paid to the government. Amazon Mexico will collect sales tax and remit to Mexico government if you don't provide RFC and CSF.
It also implies, you don't have to provide RFC and CSF. Let Amazon Mexico do the tax collection and reporting.
Here is how:
Step 1): Go to your Tax settings, as show in figure 1.
Figure 2. Tax setting on Amazon Mexico
Step 2: Answer to to questions: "Do you have a RFC ID" or "Do you have CSF"
Figure 3. Answer no to question about RFC or CSF
Step 3: Go to FBA shipment, try to create a FBA shipment to Mexico. If allows you to create FBA shipment, then you are all set. Make sure you use a Mexico address as "Ship From" (very important). You can find the Mexico address on the dashboard of our customer portal after login.
Figure 4. Ship from address must a Mexico address
Any further questions, please contact us.