Have you written an application that issues invoices? Then you’ve probably struggled with PDF generation, for a start! (Headers don’t need to align, do they?) But there is much more to generating invoices than a pretty PDF. What information has to be on an invoice? How long should you keep an invoice? Ms. Małgorzata Dankowska, a licensed tax advisor, is here to answer your questions. In this article, she’ll discuss the fundamental legal requirements for invoices in the European Union.