recorded message supposedly from Australian Tax Office.

A particularly inept version of the tax office "fraud" scam

Caller: Machine

Told me I was under investigation by the ATO for tax fraud

Robotic voice left a message telling me my family and I are being investigated for taxation fraud and previous attempts have been made to contact me so they are now persuing charges of evasion

Caller: fake ATO

automated voice threatening with a warrant.

Im being investigated for tax fraud and after multiple attempts to contact (pretty sure the ATO would have called me direct without the American accent) they said legal proceedings would follow --- then they simply hung up. Automated message.

I rang once and got disconnected