Legal analysis: 1. After receiving the message that the invoice is missing, log in to the system, query the corresponding invoice and confirm the information of the invoice with the person in charge. After obtaining accurate invoice loss information, it will be invalidated.

2. Confirm whether the invoice has been taxed. Lost invoices can be invalidated before tax returns. If the corresponding tax has been paid before this tax return, or more, then voiding is basically invalid. If you haven't filed a tax return, you can void it.

3. Invalid handling. After logging into the system to find the corresponding invoice, it will be void. After voiding, the system will record the voiding operation and the original invoice will be voided.

Legal basis: Detailed Rules for the Implementation of the Measures for the Administration of Invoices in People's Republic of China (PRC) Article 31 Units and individuals that use invoices shall properly keep them. When the invoice is lost, it shall be reported to the tax authorities in writing on the day of discovery, and it shall be declared invalid in the newspaper.