The Inland Revenue Department is warning people to be wary of online companies offering free tax return services.
This follows a number of complaints from people who say they didn't realise what they were getting themselves into.
It's ads like the current tax refund ones that Donna DeCleene thinking she was in for a windfall.
"I thought I may as well register and see if I have any money owed," DeCleene says.
She went to taxrefunds.co.nz and typed in her IRD number to find out more about claiming back taxes.
But she was surprised when she received a letter from the Inland Revenue informing her that taxrefunds.co.nz would act on her behalf on all future returns.
"They were telling you to apply for old refunds not saying that they would then act for you in future years for any tax refunds," she says.
The IRD says its received dozens of similar complaints about tax refund companies
"Read the fine print so you know what you are committing to before you do it. Or alternatively come to our website directly and you can do it for yourself anyway," says Charles Ronaldson, Inland revenue.
When logging onto taxrefunds.co.nz you can see in the fine print that the company takes 12.5% on any refund, a commission that is also paid on things like family assistance credits and they will continue acting as your tax agent until you tell the IRD otherwise.
"It tells you on the site and you have to tick a box that accepts the conditions that we will be your tax agent like any chartered accountancy," says Geoff Matthews, taxrefunds.co.nz.
Taxrefunds.co.nz was set up seven months ago and has already processed $62 million worth of returns
"I know I get a tax return through family assistance si i know i didn't need them helping me because it's all automated through IRD," says DeCleene.
However Matthews says, "if we weren't in the market nobody would know that they were due tax refunds".