As the name implies, this is an agreement through which an individual assigns rights in an intellectual property to another. Startups are built on a lot of intangible property, inclusive of skills and know-how. When people come together to start a business, their primary contribution usually entails this intangible property, and it needs to be assigned to the startup. The means of doing this is through an IP Assignment Agreement. It should be one of the first documents entered into by founders once they incorporate an entity, i.e. assign all the IP rights used to build or develop the startup to the company. Same also goes for others you engage to work on the startup.