BUT...also @pcumming
Ouch...NC has just posted a recent notice that they won't be accepting NC tax returns until 3 Feb....whether this means that TTX e-filing will be entirely stopped or not, is unknown...but NC won't be doing anything with them....yet...
What to Expect When Filing Taxes This Year | NCDOR
Safer to just wait until after 3 Feb to e-file NC...you may get some more tax forms in the mail you "forgot" about.
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And even if NC takes your submission from TTX sooner as a test file, they claim they won't do anything with them until 3 Feb.