The face value of the invoice is lower than the face value of the invoice provided. 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. Underinvoicing is the behavior that the invoice face value is lower than the provided invoice face value. Buying a house refers to buying a commercial house from a real estate developer or other development unit, or buying a second-hand house from other real estate owners, obtaining detailed information of the house through advertisements, and making a decision to buy after comparison.