When state income calculations are tied to federal AGI, it only means that it is the starting point, and it can and should be adjusted when needed. For example, VA provides additions to income

- Interest on obligations of other states

- Interest on federally exempt U.S. obligations

These are items not taxable to federal and not included in federal AGI but are taxable to VA and should be included in state AGI. The dividends and capital gains are taxable items in federal and should be included in VA because they are taxable to VA as well. I put them in "Other - Enter the amount of any other income not included in federal adjusted gross income, which is taxable in Virginia".

The nonresidents cannot take standard deduction, and VA specifically says it keeps it the same as the federal, so nonresidents will take itemized deduction even when they have nothing to itemize. It does not seem to be fair, but there is no other way permitted by the letter of the law. Other states for example, CA and MD, provide a choice.