Invoice serial number refers to the invoice number in the upper left corner (or upper right corner) of the invoice. If two or more consecutive invoice numbers are connected or similar, they are consecutive invoices. Connected invoices can be determined to come from the same billing company, and similar invoices depend on the specific situation.

Legal basis:

Measures for the Administration of Invoices in People's Republic of China (PRC) Article 20 Units and individuals engaged in production and business activities shall ask the payee for invoices when purchasing commodities, receiving services and engaging in other business activities. When obtaining the invoice, you are not allowed to change the name and amount.