A South Auckland man who defrauded more than $930,000 from his clients and Inland Revenue, spending some on cars and overseas holidays, has been jailed for four years.

Pranesh Nandan, a migrant from Fiji, established Nesh and Jay's Accounting Professionals Limited in Manukau in 2013, despite having no accounting qualifications.

He generated clients mainly through social media, claiming to be a chartered accountant.

Over a three-year period, Nandan filed 68 false GST returns on behalf of his clients and entities he controlled.

The returns contained significantly inflated expenses, resulting in refunds of $652,064 being paid into his accounts.

Inland Revenue said Nandan spent more than $285,000 on cars and overseas travel, which had been deposited into Nesh and Jay's bank accounts by clients to meet their tax obligations.

The total amount of money defrauded from Inland Revenue and his clients was $937,370.

Patrick Goggins, Inland Revenue's group manager investigations and advice, says Nanden was an opportunist who played on his clients' trustworthy natures.

"He came up with a devious plan to rip off honest New Zealand taxpayers and his clients, (who were) completely unaware he was making these false claims on their behalf, or that his claim to be a chartered accountant was a lie," he said.

Nandan admitted his offending when confronted by Inland Revenue, Mr Goggins said.