Housing New Zealand is being criticised for spending millions of dollars on a business case for a new computer programme.
The state corporation is defending its investment on the grounds its existing software is 17 years old and overdue for replacement.
Housing New Zealand chief executive Lesley McTurk has told MPs the revamp could save up to $70 million a year.
However, the Labour Party's housing spokesperson, Moana Mackey, says the corporation has been unable to say exactly how this would be achieved.
She says Housing New Zealand insiders have told her the business scoping case alone has so far cost about $20 million, far more than the $6 million claimed by management.
Ms Mackey questions whether replacing the software system, which she says by all accounts does not need to be replaced, is a priority in the current environment of public sector cuts.
Housing New Zealand says the current tenancy and asset management system needs to be replaced before services are compromised.
A spokesperson for the corporation, Nick Maling, disputes Ms Mackey's claims that the project has cost $20 million.
He says the business case will be submitted to the minister later this month.
Mr Maling says it doesn't make sense to keep spending money on systems that are outdated and inefficient.