Concern about a lack of consultation on the High-Wealth Individuals Research Project

It's aimed at figuring out how much the ultra rich pay in tax, as a share of their economic wealth.

Inland Revenue's started writing to 400 New Zealanders with a net worth of at least 20-million dollars, asking about their assets.

PWC partner Geof Nightingale says the Government's using a power to collect this data, it didn't consult on and was rushed through.

He says it's conducting a highly intrusive process with a power they granted themselves with no scrutiny.