The steps for red-ink offset of sub-invoices are as follows: 1. Record the invoice number and code that need red offset; 2. Taxpayers enter the anti-counterfeiting invoicing and enter the interface of filling in ordinary invoices; 3. Click the negative button above and enter the invoice code and number to be red-offset in the pop-up input box, which needs to be entered twice; 4. After confirmation, the system will bring up the corresponding positive invoice. As long as the quantity and unit are negative and confirmed, the system will generate red-ink documents and then print red-ink invoices.