To resolve the Error: 'ABN/WPN is invalid, please check & edit item':
Log in to HandiTax, and select your client and their tax return.
Click on the Main form I, and click Edit.
if data is present at item 1, in Your main salary and wage occupation, Payer's ABN, Payer's Name, or any value and type fields, without other details entered, complete missing information as required or remove unnecessary data.
Tip: Item 1 is a repeatable section, so check each section for any entries too.