Guidance on monthly invoice issuance

On October 10, 2025, the Da Nang City Tax Department issued Official Letter No. 1820/DAN-QLDN2 (“Official Letter”) to address enterprises’ inquiries regarding the timing of invoice issuance and the delivery of goods and services at the end of the month in accordance with regulations on invoices and supporting documents.

The Official Letter reaffirms the general principle that the time of invoice issuance is the time when ownership or the right to use goods is transferred to the buyer, or when the provision of services is completed.

Only in cases involving the sale of goods or the provision of services in large quantities and on a frequent basis—such as electricity, water supply, television, telecommunications, securities, computerized lottery, and transportation support services for railway, road, and aviation—may the seller issue monthly invoices based on an agreed-upon billing cycle between the parties.

Accordingly, the Official Letter emphasizes that for transactions not falling under the aforementioned categories, enterprises are not permitted to issue invoices on a monthly basis, even if the parties have a written agreement stipulating the issuance of monthly invoices.