I forgot a w2 for my 2023 taxes. I had income already filed which was in a nonresident state (NC). The new income to add is the state I resided in (GA). Do I need to amend both states or can I amend just Georgia?
If you the income does not affect your North Carolina return, then you would only need to Amend Your Return for GA and your federal return. You would not need to do anything with NC
could you specify more on how the income in Georgia would affect North Carolinas? This Georgia income is a w2.
For nonresidents and part-year residents, North Carolina uses what's called a "state income percentage" method for residents. The income percentage is calculated based on North Carolina Net Income/Everywhere Net Income. The state starts with taxable income based on income from all states and then multiplies that income by the income percentage to get your North Carolina taxable income.
Because of this, changes to your overall income - even the income outside of North Carolina - can impact your North Carolina taxable income. So, even though the Georgia income itself isn't directly taxed by North Carolina, it can impact the calculation of your overall tax liability in North Carolina.
You may need to amend your North Carolina return even though your income isn't North Carolina source income. You can set up your North Carolina amendment and then add the W-2 to see if it changes your North Carolina liability.