Hi, 

Thank you so much for your question, I would suggest double checking the income amounts on both Turbo Tax, as well as the express NOA, its possible that you may not have received all the slips that the CRA has on file, the additional income on those slips could result in a higher total payable amount. Its also possible that there may have been a data entry error, its always good practice to double check the amounts you've entered. 

Hope this helps! Happy tax filing!