I will be completing a project in another state, and I will be paid as an independent contractor (and issued a 1099). I will be working in my own state and submitting my work when done with the project. As far as I understand, I am only required to pay federal income tax and self employment tax on this. Because I will not perform the work in the other state, I won't have to pay that state's income tax. (My state of residence does not have an income tax, so that isn't a factor.)
Will I ever need to prove to this other state that I performed the work at home? If so, what kind of documentation would suffice?