Invoice size is generally A5 paper size of 148mm×2 10mm, and there are also some larger or smaller invoices, but they are hardly common. In addition to the size, the layout and content of invoices also have standard requirements for identification and verification in the tax department.

Invoice refers to the business vouchers issued and collected by all units and individuals in buying and selling goods, providing or receiving services and engaging in other business activities. It is the original basis of accounting, and it is also an important basis for law enforcement inspection by audit institutions and tax authorities.