Validar RFC en PHP
^([A-Z]{3,4})(\d{2}(?:0[1-9]|1[0-2])(?:0[1-9]|[12]\d|3[01]))([A-Z\d]{2}(?:[A\d]))?$
laura yaritzi muñoz muñoz
^([A-Z]{3,4})(\d{2}(?:0[1-9]|1[0-2])(?:0[1-9]|[12]\d|3[01]))([A-Z\d]{2}(?:[A\d]))?$