I understand that a raise in your balance owing after being reassessed is upsetting, but these kinds of changes are common. Please see this TurboTax FAQ for more information: Why is the refund or balance owing on my Notice of Assessment different from what TurboTax calculate...

If you are still believe that there was a calculation error within the software, please contact our phone support team for more assistance. You can use the form on this page to get the right phone number to call: TurboTax Contact Us