Everything's negotiable, and IP is definitely something you should negotiate, but often there's a process for this that legal has approved and changing it is a dealbreaker.<p>A typical process is that you "disclaim" up front all the IP you take into the company, and they own everything after that.<p>A typical exception to that process that might be accepted is that they own everything related to their business that you come up with after you join the company.<p>An exception that can be pretty hard to get is that you own everything you come up with off-hours. This is reasonable, (though obviously you can disagree and turn the job down): if the company is providing you access to knowledge and domain exposure, you shouldn't be exploiting it to start your own business on the side. Also, it can be hard for them to pinpoint exactly when you came up with something, which creates legal headaches down the road.