The information came from a National Party Official Information Act (OIA) request which confirmed the tests were done verbally.
Collins said this was not good enough.
"Twyford's underwrites guarantee a minimum price for KiwiBuild homes that don't sell, shifting the risk from the developer to the taxpayer.
"Conversations are hardly a robust assessment of whether these homes will present a risk to the taxpayer, which is a real possibility given the shambles KiwiBuild has been to date."
As promised, Twyford's office did go back to National to clarify the request.
"Officials have records, which are commercially confidential, relating to the discussions with the developer on issues of the agreement, including additionality," an email to National said.
"However, there is no 'additionality assessment' and it was on that basis that reply stated there is no further written documentation."
Speaking to media after question time, Twyford said there was a detailed assessment of the additionality test but that was a matter for the Ministry [of Housing and Urban Development.]"
"They tell me there is a number of documents and communications that they'll provide."
There were four main areas of the test, but Twyford was unable to say, off the top of his head what they were.
When pressed, he said he was not "here to do a pop quiz".
But he said elements of the test did include doing things like bringing properties to market "quicker than they otherwise would have been"\.
However, he did not seem too concerned with the issue.
"This is a minor operational detail and I'm not fussed about it."
He said it was a matter for the chief executive of the Ministry of Housing and Urban Development.
"Where or not it's worth him fronting up on camera to answer questions about minor operational detail, I honestly doubt that."
