Desktop application in C # of a tax office assistant that performs some functions such as: Generate XML from MDFe (Electronic Manifesto of Tax Documents) from the XML of an invoice, interact with invoices in PDF and consult from a CNPJ or IE if a customer has issues with the IRS. In this project it is possible to observe the use of: Manipulation of PDF files as location and data extraction, reordering and counting pages and merging PDFs; Manipulation of CSV files; Spreadsheet manipulation; CRUD in the configuration file (App Settings); XML serialization; Background threads (BackgroundWorker); Decompression of zipped files; Monitor changes in files and folders (FileSystemWatcher); Calls to the Windows API (Microsoft.Win32); Regex expressions; Interaction with the DOM of a web page through the HTMLDocument interface