The Tax Office has admitted paying out more than $1.6 billion in fake GST claims as part of a $4.6 billion fraud based on a simple scheme promoted on social media platform TikTok – a total that is twice previous reports and the biggest tax fraud in Australian history.

The fraud was uncovered by Westpac and other banks, some of which passed on a series of alerts to the Tax Office from 2020. But after being frustrated by the apparent lack of action by the Tax Office, some bank staff shared their concerns informally with the Reserve Bank, which then alerted Treasury and the Tax Office in February last year.