The Fapiao is just an official invoice, you need to ask for one when you buy things that you need to declare or if you are paying in name of other person or company, for example i get many sample materials, tools and hardware for the office, dinners with clients, etc. anything you pay you can get a Fapiao, i just have my business card with the company name (in chinese) and show it to them, they write the fapiao with the company name so i can just give the fapiao to anyone in the office and get the money back, anything else in a regular day basis you don’t need a Fapiao for anything.