Hi, (forgive the sorta anonymous name)
> I (a US Citizen) live overseas and my spouse (also a US Citizen) works
> a normal job for a company here, and I'm self-employed.
>
> Filling out her taxes is relatively straight-forward, however, my
> question is about my taxes. Do I have to fill out the business forms
> as if I had my business in the US (listing all expenses and so on,
> mileage and whatever) or is it enough to say that we earned $X
> together overseas and that's the value that should be used as the > gross income?
Yes. Schedule C or F, just as if you were in the U.S.