Hi ahmednihal50-gma,
Welcome to Community! QuickBooks Online provides the valuable features you need for tracking and recording billable time for subcontractor's. It's essential that you're able to provide a record of what you've paid. I'll be glad to assist!
To prepare and export the T4A forms, please refer to this article for the steps and additional information for verifying payment amounts and filing with the CRA.
Should you require additional assistance, please reach out to your accountant for their expertise. If you don't have an accountant, we can help you locate a ProAdvisor in your local area.
Feel free to post other questions. We'd be happy to help!