A number of websites offer to do simple tax returns for PAYE earners and only submit them to the IRD when a refund is due. They take their fee as a cut of that refund.
Another option is to use the IRD's free online service.
Cilla Hegarty, of NZ Tax Refunds, said too few people knew whether they were paying the right tax.
"Financial literacy is appalling. Some of the young ones, I don't think they even know they're paying tax. They just get the money in their hands and spend it.
"I'm appalled at the lack of understanding and the lack of interest."
She said workers would often have overpaid tax if their circumstances changed during a year — such as if they had received a bonus, started a new job or taken parental leave.
NZ Tax Refunds has 300,000 to 400,000 taxpayers on its database and Hegarty said 93 per cent of the people who contacted the company had overpaid tax at some stage. The average refund was about $460.
"If you've overpaid your tax, that's your money and you should get it back," she said.
Her site has recently launched an app, which charges less commission than its website.
Hegarty said fees companies charged for refunds could be claimed as an expense in the next tax return. "It's one of the few minor things that you can claim as a salary earner but your refund fee is effectively subsidised by the Government."
Last year, the company's biggest refund was $36,000. "We've advised her in future what her tax code should be."
Hegarty said people would use their refunds for anything from shoes to engagement rings. "Different amounts of money make different people happy."
Many accountants will also do a tax return for PAYE workers for less than $100, but the fee has to be paid whether there is a refund due or not.
Palmerston North woman Emma Maw decided to try for a refund with NZ Tax Refunds last year when her husband received an email saying if a friend signed up for the site, he would get a petrol voucher.
"It never really showed how much of the refund they took," Maw said. "The email I got was just what I was going to be given and I guess being a working family, the ease of it all just being in my bank account without having to do anything was kind of handy."
She said the family received $1,215 from a recalculation of Working for Families credits and she received $268 personally, after fees.
She said she had been planning to use the site this year but finding out it would cost her 19.5 per cent could change her mind.
An IRD spokesperson said the department encouraged people to use its online services.
"You can go online and check if you are due a refund using the myIR online service.
"This is a free and easy service and if you think you are due a refund, you can request a personal tax summary and you will receive this refund directly into your bank account."
The cheapest fee for a straightforward return was offered by Meanasrefunds.co.nz, which charges $30 plus GST.
Director Carter Hawkins said 87 per cent of his clients were due a refund, and the average was $526.
