The National Anti-Corruption Commission Inspector has announced she has launched a formal investigation into the regulator’s refusal to investigate six public officials referred by the Royal Commission into Robodebt.

For anyone missing the significance, the Inspector announced "looking into" complaints about the NACC decision months ago, but this is the first time the word "investigation" has been used.

The distinction is important because once a formal “investigation” is commenced the NACC Inspector has additional powers, including the power to obtain documents.