legal ground
Article 2 of the Detailed Rules for the Implementation of the Measures for the Administration of Invoices of the People's Republic of China
Invoices with uniform styles throughout the country shall be determined by State Taxation Administration of The People's Republic of China.
Invoices with uniform patterns within provinces, autonomous regions and municipalities directly under the Central Government shall be determined by the tax bureaus of provinces, autonomous regions and municipalities directly under the Central Government (hereinafter referred to as provincial tax bureaus).
Article 31
Units and individuals that use invoices shall properly keep invoices. When the invoice is lost, it shall be reported to the tax authorities in writing on the day when the loss is found.
Article 27
After the invoice is issued, if the red-ink invoice is required for the return of sales, the original invoice must be recovered and marked "invalid" or valid proof from the other party must be obtained.
After issuing the invoice, if there is a sales discount, you must reissue the sales invoice after recovering the original invoice and marking it as "invalid" or issue a red-ink invoice after obtaining the valid certificate from the other party.