Is there a way of modifying a T4 to add the Automobile Tax Benefit figures to Box 14 and 34 of the T4 before I submit to the CRA?

Hi there huronwatersupply,

it's important that all your payroll is entered correctly so your employees are paid the correct amounts. QuickBooks Online Payroll is a great tool able to help you keep track of the pay given to employees for their hours worked so that you can generate year-end forms. I can point you in the right direction for assistance editing your T4 slips.

For assistance in editing your T4 slips, you'd need to reach out to the QuickBooks Online Support team outside of the Community. They'll be able to view your T4 slips with you in a secure setting in order to assist with editing them. You can reach them using these steps:

Schedule a Callback or start a Chat: click (?)Help in the upper right > type and enter "Contact support" into the QB Assistant > click Contact Us > explain your situation > click Let's Talk > choose Get a callback or Start a Chat.
Social Media: Facebook and Twitter

If you have any other questions, feel free to reach out here.