An entity that accepts or rejects tax documents after verifying their compliance to essential aspects and ensuring their validity. OSE not only validates the correct issuance of a CPE (Comprobante de Pago Electrónico), but also sends the validation information to SUNAT (Superintendencia Nacional de Aduanas y de Administración Tributaria), along with the related documents. For more details regarding how an OSE operates, see the SUNAT web page.