Can I request the ITIN number for my mother online, by email or by mail if she is currently living in Mexico?

To obtain an ITIN, you must complete IRS Form W-7, IRS Application for Individual Taxpayer Identification Number. The Form W-7 requires documentation substantiating foreign/alien status and true identity for each individual. You can mail the documentation, along with the Form W-7, to the address shown in the Form W-7 Instruction. Form W-7(SP), Solicitud de Número de Identificación Personal del Contribuyente del Servicio de Impuestos Internos is available for use by Spanish speakers.

Obtaining an ITIN from Abroad