Hackers are stealing millions of dollars by pinching personal information and breaking into people's tax accounts.
Australia's tax watchdog wants anyone who has noticed suspicious refund claims to get in touch.
The inspector-general has received more than 130 complaint cases in the last 18 months.
"We're concerned about people who have had their identity compromised, and then someone has used that information to go into their tax accounts and update their tax accounts in an unauthorised way, and then start claiming refunds or amendments which result in refunds they're not entitled to," Inspector-General Karen Payne told ABC Radio.
Scammers might make contact via a phone call or text requesting an individual updates their tax information, only to use those details to lodge a claim.
"There have been instances where people have got a text - 'please update your details, click this link'," Ms Payne said.
"Don't do that, that's a scam."
The inspector-general has some ideas and views about what is happening but wants anyone affected to share their experience.
Tax agents who've seen dodgy activity on a client's account should get involved, as should anyone who's got a text requesting they update their tax details by clicking a link.
The investigation will expand on a major operation that started last year focused on offenders inventing fake businesses and lodging false Australian business number applications to rort the tax system.
