In most cases the Canada Revenue Agency (CRA) will explain how they calculated the amount of your refund/balance owing. You will find this information on your Notice of Assessment (NoA). You can compare the line numbers on your NoA with your tax return to see what the CRA changed. 

If there is a difference between calculations you can complete the following: How do I submit a claim under the TurboTax 100% Accurate Calculations Guarantee?

Thank you for choosing TurboTax.

In my CRA account it said that they changed the total payable because of a calculation error.  As for the process with TurboTax. Do they make give you and any refund if you don't actually have any payable, interest or penalty? My refund was reduced by $80. There was not any interest or penalty since I didn't have to put out any money.  I still got a refund but smaller.

You can submit a claim under the TurboTax Maximum Refund Guarantee.

Thank you for choosing TurboTax.