ATO error code: CMN.ATO.GEN.XML03

Hello Kiwiphill 

This error means there's an invalid character somewhere in your in your payroll information in MYOB. Invalid characters are "[ ] ! # $ % * ; = @ <>\ _ { } ^~`"

You'll need to check for (and remove) any invalid characters in your employee cards and payroll category names.

I have attached a Help Article on how to fix rejected reports in single-touch payroll which covers this error code as well as some other ones and how to resolve them.

Please let me know how you go.