The Australian Taxation Office has moved to reassure taxpayers that its systems remain secure following reports of hackers stealing thousands of dollars through fraudulent tax returns, with some victims losing more than $A14,000.

The ATO issued a statement denying that its systems had been compromised, describing media reports of a "hack" as incorrect. However, multiple taxpayers have come forward reporting that criminals had infiltrated their myGov accounts, filed bogus tax returns, and redirected refunds to fraudulent bank accounts.

"The ATO's systems are secure, resilient and have not been compromised," the tax office said in its statement.

"The safety of taxpayers' information is of the utmost importance to us, and the ATO continues to remain vigilant for new and emerging cyber threats."

The ATO attributed the unusual account activity to identity theft rather than a breach of its own systems, explaining that "identity information can be compromised in a variety of ways, including requests for information by malicious actors, phishing emails, large-scale data breaches, and individual device or home network hacking."

Perth woman Kate Quinn discovered earlier this year that hackers had filed a fraudulent $8,000 tax return in her name. Her accountant found they were no longer authorised to manage her tax affairs, and her linked bank account details had been changed.

Quinn described how quickly the fraud can occur: "They hack in, they untick 'notify me or notify my tax agent' and change the bank account details," she told The Australian. "[The ATO officer] said it probably takes all of 10 to 15 seconds [to] change the bank account details and the money's gone, and the case is closed and no one's notified."

Melbourne accountant Adrian Raftery reported a similar experience with one of his clients, where hackers successfully filed a new tax return and amended the previous year's return to obtain more than $14,000 in fraudulent refunds.

The sophisticated nature of these attacks has raised concerns about the vulnerability of taxpayer accounts, particularly as tax season approaches and criminals typically increase their targeting of tax-related fraud.

Enhanced Security Measures Deployed

In response to the growing threat, the ATO said it activates "stringent security measures" when it suspects a taxpayer's identity may be compromised. The agency promised to work with victims to "fix their client account and remediate it to its true and genuine position" before working to recover stolen funds.

The tax office is also rolling out additional security features in its mobile app, including the ability for taxpayers to receive secure messages when key information such as bank account details are changed.

The ATO has urged Australians to strengthen their defences by using myID (previously myGovID) when accessing online services and setting up the highest identity strength possible "to make it harder for fraudsters to exploit their identities."

With tax season approaching, the ATO has issued fresh warnings about scam communications. The agency reminded taxpayers that while it may use SMS or email to ask people to contact them, it "will never send an unsolicited message containing a hyperlink to log on to online services."

"Always access ATO services directly by typing ato.gov.au or my.gov.au into your browser," the ATO advised.

Taxpayers who believe their personal information has been compromised or who have fallen victim to scammers are urged to contact the ATO immediately on 1800 008 540. Those whose tax affairs have been impacted should also inform their tax agent.

The ATO has not confirmed how many Australians have been affected by the fraudulent activity, the total amount of money stolen, or whether any arrests have been made in connection with the schemes.