You report the interest income on the resident return of MD, and do not need to file a NC return if that was your only income there.
If you are a nonresident, you must file if:
- you received income for the taxable year from North Carolina sources that was attributable to ownership of any interest in real or tangible personal property in the State or derived from a business, trade, profession, or occupation carried on in North Carolina, or is derived from gambling activities in this State and your total income from all sources both inside and outside the State, exceeds the amount for your filing status shown in the Filing Requirements Chart. Which starts at $8,250 for a single person and goes up.
- Source: http://www.dor.state.nc.us/taxes/individual/filing.html
