I still get royalties from a book published some 20 years ago.
That gives me the impression you are not "in the business" of writing books, and that it's not your primary source of income. So that would be reported on SCH E.
In the last few years Turbotax also insists I report them again on Schedule C.
Never heard of that in my 18 years of using the program. It's one or the other. But never both SCH C and SCH E. In general, royalty income reported in box 2 of the 1099-MISC is reported on SCH E, unless you are "in the business" of writing books, and that is the primary source of your income. If the income is reported in box 2, the program will "force" you to the SCH E - even if you've entered it in the SCH C section of the program. It takes a bit of finagling for one to force box 2 income, to the SCH C.
