After you file

The IRS will automatically apply any refund amount you would receive to your outstanding taxes still owed.  If the refund is more than what is owed you will receive the balance in the method you selected in Turbo Tax (i.e. direct deposit to a bank account, paper check, etc).  If the refund is not as much as what is owed you will continue to have the responsibility to pay the balance and should pay the amount immediately to reduce interest and penalty charges.