I have received a slip late but I have already filed my taxes. Can I refile my taxes? Do I need to purchase a separate license for the refile?

You can refile your taxes with the same license you used to make the first submission to CRA. Go to 'Form Manager' and search for the form 'Refile'. Follow the three steps as indicated on the form. For the software to allow you to do an electronic submission, the refund/balance owing amount must have changed. Then, go to 'Transmission' on the menu bar and click on 'Refile'.