Could be either....or neither...like perhaps something you miss-entered on your tax preparation.
If the balance due billing doesn't indicate why they changed it, then you'll have to call the NE Tax Dep of Rev and find out what they changed that resulted in the extra billing. They may have disallowed some fairly large income deduction, or found an error in pre-paid tax credit you claimed, or double-claimed when you filed the original forms.
For instance, if you paid 4 quarterly estimated tax payments to NE during the year, you may have entered all 4, but they might not have a record of one of the payments. Or, if you had a W-2 with NE withholding, you could have mis-keyed the $$ amount in box 17 of the W-2 ...and when they received the employers copy of that W-2, their computers noticed the difference and made the appropriate corrections...and billed you.
With a gazillion other possible issues in all sorts of tax prep areas, there is no way to investigate until you find out from NE what they changed & why...only then can you check to see what the problem was.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
