If you are encountering the error 'Submission must contain at least one attachment or an entry in the whitespace if Capital Gains Summary is present.' while trying to submit your return, there are a few things you can check and troubleshoot to resolve the issue. Here are some steps you can take:
1. Check for Required Attachments: Ensure that you have attached the "Capital Gain Computation" details in PDF format using the "Add Attachment" green button at the top of the page. This is essential when reporting any Capital Gains.
2. Verify Box 54: If you have not attached the computation details, make sure to explain in Box 54 as instructed.
3. Review the Information: Double-check all the information you have entered to ensure accuracy and completeness.
We hope that these steps help you resolve the error and successfully submit your return.