What aspect is NOT a requirement for e-invoicing?

E-invoicing is an electronic method of sending invoices, which has several requirements to ensure validity and compliance. One such aspect is the necessity for sending invoices securely to protect sensitive information and maintain the integrity of the documents. The requirement for authenticity focuses on verifying the origin of the invoice to prevent fraud and ensure it is legitimate.

The agreement of invoicing by the customer is also crucial, as it establishes mutual consent and terms that govern the transaction, ensuring that both parties are aligned on the details.

However, invoices being issued at any time is not a specific requirement of e-invoicing. While it is true that electronic invoicing can offer flexibility in terms of timing, the process is often governed by specific business practices and legal requirements that dictate when an invoice can be validly issued. Therefore, this choice emphasizes that there is no strict time constraint mandated by the e-invoicing framework itself, making it the correct answer.