Cl@ve is the electronic identification system used by Spanish public administrations, allowing access to online procedures without needing a digital certificate. It includes Cl@ve PIN, based on a one time code, and Cl@ve Permanente, based on your own password, and is used to check and file procedures with the tax agency, Social Security and other bodies.
To start using it, you first need to register in person or with a digital certificate before you can use it fully online.
kontora generates your tax forms box by box, tells you how much to set aside and reminds you before every deadline.