The Promise application opens. Special invoices for value-added tax are usually issued by enterprises in the tax bureau or its designated place in accordance with the provisions of the national tax department. Wenzhou City Taxation Bureau of State Taxation Administration of The People's Republic of China shows that with the help of the tax system and the technical support of aerospace information company, Wenzhou Water Group has realized the electronic invoice of value-added tax by mobile phone through the "Commitment" App. With the technical support of electronic invoices, the water group with millions of paper invoices a year can "go into battle lightly".