Hi Roland B,

Welcome to Community!  It's essential that you're able to electronically submit your T4 slips to the CRA.  There have been some recent updates, and you can follow this link, to review the Changes to T4, T4A, T5018 XML Filing to CRA.

Quickbooks Desktop has now added a field "Representative Identifier (RAC)" to the EFile T4 page.  This is where you will type your RepID and then Submit.  You should now be able to upload the .xml file to the CRA. 

Should you require additional assistance, please don't hesitate to contact our QuickBooks Desktop specialists at 1-833-317-2226, Mon-Fri: 9am-8pm ET.

Feel free to reach back out with any other questions.  We would be glad to help!