We didn't pay for our State taxes last year. Will it automatically be deducted from our State return? Is there a special form to fill out or box to check?

If you owed state taxes on the 2016 tax return which were not paid and have a tax refund on the 2017 tax return, then the state will seize the 2017 tax refund and apply the amount to the back taxes owed.  If the refund satisfies the debt then the state will send you the remainder of the refund.  If the refund does not satisfy the debt then the state will send you a bill in the mail for the balance to include any penalties and interest.

There is nothing that you can enter on the 2017 state tax return indicating you have state back taxes owed.