Why do I owe state

If you owe state income taxes, do a line by line comparison of this year's return versus last year's return to identify any differences.

 

 Also, double check the amounts you entered into TurboTax to make sure they were entered correctly.

 

Below are additional reasons why you may owe state income tax compared to last year: 

• Your 2019 State Tax Withholding was lower than 2018.
• You didn't defer or you deferred less income into your Employer-Sponsored Retirement Plan or Flexible Savings Plan.
• You didn't qualify for a tax credit you you received last year (or the credit amount decreased).
• You removed a dependent.
• You changed your filing status.
• If you didn't itemize your deductions in 2019 but you itemized your deductions in 2018 or you are using the Standard Deduction in 2019.

Additional information: Why did my refund go down compared to last year's?

How can I make sure I didn’t make any mistakes causing my state to become owed ? This is the first ever so I’m lost 

The best thing to do is compare it with your return from the previous year. Make sure you have entries on the same lines and that the numbers make sense based on the descriptions for them. Compare your entries with your source documents, like your W-2 forms.