IRD investigations and advice group manager Patrick Goggin said Nandan was an "opportunist fraudster who thought he could cheat the tax system by playing on his clients' trustworthy nature".
"Mr Nandan came up with a devious plan to rip off honest New Zealand taxpayers and his clients, and then spent nearly a million dollars on overseas travel and flash European cars," he said.
"His clients were completely unaware he was making these false claims on their behalf or that his claim to be a chartered accountant was a lie."
When confronted by IRD, Nandan admitted he had made up the figures in false returns.
"We take this sort of offending extremely seriously and the public should be assured that tax cheats won't get away with stealing money that would normally go towards funding vital services such as hospitals, schools and roads," Goggin said.