Charles Hedburg tried to rip off the IRD by claiming his businesses had expenses that far outweighed their income.

A plot to scam the New Zealand tax department of more than $1 million appears to have needed "zero sophistication," a district court judge says.

Charles George Hedberg, who runs a lawnmowing business in New Plymouth and also works as a petrol station forecourt assistant, claimed he had expenses of $800,000 and $10m in two separate GST returns he filed online with Inland Revenue Department (IRD) last year.

The financial information was completely false but it netted him a $100,000 refund first time around before IRD smelt a rat when Hedberg decided to become more ambitious in his criminal endeavours.

MAARTEN HOLL/STUFF A New Plymouth man fudged his tax information twice. The first time it netted him $100,000 but the next one resulted in court action. (File Photo)

Judge Garry Barkle said that on May 5, 2017, Hedberg filed a GST return for the period ending March 31, 2017, which stated his lawnmowing business had earned income of $10,000 while incurring expenses totalling $800,000.

The $100,000 refund calculated was subsequently paid into his company's account.

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The judge said Hedberg, no doubt buoyed by this initial success, then launched another outlandish attempt to get even more cash.

On September 4, 2017, the defendant filed another return for the period ending September 30, 2017.

In that application, he told IRD he received an income of $50,000 but had expenses of $10m. Based on those figures, a refund of $1.4m was calculated but the size of this sum rung alarm bells with IRD staff, who launched an investigation.

"Without any surprise that amount was not released," Judge Barkle said.

After a full re-assessment, it was established that Hedberg was only entitled to a refund of $542.60.

The New Plymouth District Court heard how the defendant, who previously pleaded guilty to two charges of knowingly filing false tax information, spent some of the $100,000 refund on a new car and an overseas holiday but ended up having to sell his home to pay the money back.

"That's a big call. I haven't had many standing there who have been prepared to do that," the judge told Hedberg.

The judge was surprised at how easy it had been for Hedberg to fudge the numbers and said the offending appeared to have required "zero sophistication".

"It seems baffling that someone can manipulate the figures with such ease as you did," he said.

Hedberg was interviewed days after the ruse was discovered and had fully co-operated with IRD through the process.

At last week's hearing, prosecutor Jacob Bourke, who appeared on behalf of IRD, said there had been clear premeditation involved in the offending, which had a direct impact on the "back pocket" of taxpayers.

Bourke said he accepted Hedberg's remorse and that the $100,000 had been paid back but still sought jail time as the starting point for the offending. He said an electronically monitored sentence was not opposed in this case.

Defence lawyer Kylie Pascoe asked Judge Barkle to follow the recommendation made by the probation service and impose a sentence of supervision.

She said IRD had failed to take into account Hedberg's personal circumstances, including his intellectual impairment and learning deficits.

While Pascoe said the defendant knew right from wrong, he displayed a level of naivety about his actions and failed to recognise the seriousness what he had done.

She said the offending required no skill or sophistication and Hedberg deserved credit for his early guilty pleas and remorse. Pascoe said her client had also engaged the services of an accountant to assist with his financial matters.

Hedberg was sentenced to three months' community detention and a year-long period of supervision.