Usually when a letter with a balance is sent, it includes the reasons why the changes were made that caused the balance. Review the letter and compare the numbers to your return. Some of the most common reasons why this could happen is if:
- Incorrect numbers were entered in the return, like the wrong amount for withholdings
- There might be penalties for late payment or filings
- They contact taxpayers if the return hasn't been filed
If they didn't send you the reason you have the balance, contact them and ask them for more information. If you disagree with the balance, you need to respond to the state.