Do I need to make an appointment to buy invoices on the self-service machine of Changsha Taxation Bureau?

no need. According to the information on the website of Changsha Taxation Bureau, you don't need to make an appointment to buy invoices on the self-service machine of Changsha Taxation Bureau. You just need to follow the instructions at the self-service tax terminal in the self-service ticket collection area, and the system will generate the electronic ticket number sequence of invoice collection in the background in real time, with the "electronic ticket number of invoice" printed by the terminal. The tax bureau is the government agency in charge of tax work, and undertakes the duties of tax and non-tax revenue collection and management within its jurisdiction.