1. They would own everything by default from the point you join the company. Even if you do not declare past projects in the form, they cannot own it if you c

1. They would own everything by default from the point you join the company. Even if you do not declare past projects in the form, they cannot own it if you can prove that those were past projects from before you joined. Declaring just makes things easier. One company asked me for proof of prior existence of these projects; their proposal was to keep my pre-existing source code in an immutable vault that both parties could access in case of a lawsuit, just before I join the company. 2. "New" side projects may not be covered by such declarations, which are about the past. So if you want to continue some side projects, you should read the language of the agreement carefully, and/or, reach an agreement in writing with them that you are working on the said side projects and this is OK with them.