Jay Hello !
Design is not just what it looks like and feels like. Design is how it works.
要先向國稅局申辦「統一發票購票證」，然後要去用這個證買發票，然後才能開給客戶一張發票，若是公司已經在正常申報營業稅，那麼購票證應該已經申請下來。