If tax returns are rejected, check that your Tax Agent details are correct in the software.
Log in to HandiTax.
Go to Options, then Tax Form Options to confirm your agent details.
Click TaxForms, then Edit to open the Client's Tax Form Details window and check the assigned agent.
Make sure you're using the latest version of the software. Go to Help, then About, then Software Updates to check.
If the issue continues, contact the ATO to investigate the backend error. Provide the Transaction ID and Message ID from the rejected Validation report.