In Mexico, every taxpayer needs a valid registration with SAT to carry out official procedures, issue invoices, or apply for government benefits. This registration is called the
RFC CON HOMOCLAVE
The RFC is your Registro Federal de Contribuyentes, and the homoclave is a unique three-character code that gets added at the end. Together, they form your complete tax ID. Without the homoclave, your RFC is considered incomplete, which means you can face problema.