The Australian Competition and Consumer Commission wants Australians to just hang up on tax scammers.
The advice comes after more than $1 million has already been reported lost to Scamwatch this year in tax scams.
These telephone scams can come in many forms, but generally claim the victim has underpaid their taxes and are required to pay the "debt" immediately.
The ACCC's deputy chair Delia Rickard said scammers often use threats of frightening repercussions.
"Tax scammers are particularly aggressive so many people feel pressured to pay quickly without questioning them," Mr Rickard said.
"The most threatening scammers even say that police are on their way to arrest you but can be stopped if you pay immediately."
Personal information found online is usually used to convince the victim the caller is legitimate.
The callers then ask for payment of an "unpaid debt" via money transfer, credit card, direct debit cards or even iTunes cards.
In many cases, the call looks like it comes from a local phone number, but the Australian Tax Office (ATO) warns the scammers are calling from overseas using voice over internal protocol (VOIP) software.
Some scammers are also using emails to try gain personal information, such as tax file numbers and banking and credit card details.
Mr Rickard said just hang up or press delete if you receive a call or email out of the blue from someone claiming they are from the ATO and asking for money or personal details.
"You can check whether they're the real deal by calling the ATO on its official contact number - 1800-008-540."
Any unusual requests for money or personal information should be treated as highly suspicious.
"If you hand over your personal information to a scammer, they can use it for identify theft or to commit other crimes," Mr Rickard said.
While the ATO does often make phone calls and emails, it would never ask for personal details or cold call about a debt and make aggressive threats.
ATO email scams can be reported by forwarding the original email to ReportEmailFraud@ato.gov.au or by calling the ACCC via Scamwatch on 1300-795-995.
