there are two concepts - residence and domicile.  a taxpayer's state of residence can be the same as their state of domicile. but some taxpayers move from state to state during the year and are considered residents of each state - ballplayers, for example, have to file tax returns in every state they play in that has an income tax even though they are residents for only a few days a year.  domicile is what a taxpayer treats as their permanent place of abode.

your nephew needs to file a part-year resident return for NC. if using TurboTax this must be prepared first.  then he needs to prepare a resident state return for PA where all his income will be reported. he will get full or partial credit for the state income tax liability in NC 

Thank you!

Opinion:

I'm going to disagree with the part-year NC csuggestion......He was only in NC a short time, did not remain in NC, and certainly was not there over 6 mos....when he might have been forced into doing a part-year resident tax return for NC.

File non-resident for NC and full yearresident for PA.   After completely filling out the Federal tax return, make sure the NC non-resident tax return is worked on first.....And then the PA full year resident tax return....and take a credit for taxes paid to NC on the PA tax return.

Do not indicate he moved to-or-from PA during the year,   but indicate NC as an "Other" state he worked in during 2020.  

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But that's my opinion as another software user.