@TLM5 NY has this 'wierd' law that separates who is working for a NY firm from another state between those who are working outside of NY for their personal convenience and those that are required to work in the other state?
which defines your situation? are you working from NC at your convenience or does your job (and therefore your employer) require you to be in NC to do your job? it's another way of asking, 'why is your employer withholding NY tax and not NC tax"?
