There are two different areas on the NC Department of Revenue where you can pay a tax bill. One for paying when you have received a notice from them (in which case you would have a 'notice number') and one for simply paying your state balance due amount after filing your taxes.
Here is the link to the area where you would pay your state balance due amount (no notice number required):
Here is the link to the area where you would pay a tax bill with a notice number:
Finding the notice number that I never had to use during prior years was driving me crazy. I just spent an hour looking through emails and docs for this number, when turns out (thanks to you), I never had a notice number because I didn't need it to pay my taxes. Other posters asked this question and the responses are incorrect! Thank you so much for the other link AnnetteB!!