Acerca del Formulario W-9
https://www.irs.gov/forms-pubs/about-form-w-9
Acerca del formulario W-8 BEN
https://www.irs.gov/forms-pubs/about-form-w-8-ben
Instrucciones para el Formulario W-8BEN
https://www.irs.gov/instructions/iw8ben
Acerca del formulario W-8 BEN-E
https://www.irs.gov/forms-pubs/about-form-w-8-ben-e
Acerca del Formulario 1099-MISC
https://www.irs.gov/forms-pubs/about-form-1099-misc
Acerca del Formulario 1042-S
https://www.irs.gov/forms-pubs/about-form-1042-s
Tratado fiscal
https://www.irs.gov/individuals/international-taxpayers/tax-treaty-tables
Las tasas de impuestos
https://www.irs.gov/pub/irs-utl/Tax_Treaty_Table_1_2019_Feb.pdf