Incorrect tax details are being supplied to the government in nearly one in every 20 property transactions.
In 2015, the government brought in new rules for property investors and foreign buyers to supply their IRD or foreign tax numbers when buying or selling property.
But figures released by Inland Revenue showed between 1 October 2015 and 31 December 2016 - 12,500 numbers provided were incorrect.
New Zealand First leader Winston Peters said that was far too high to be explained away by human error.
"In this computerised age - where you can't make a mistake like that because all you have to do is transfer the information - somebody, or a lot of them, seem to be lying."
However, Inland Revenue said there was an error rate of between 3 and 5 percent across all its forms when they are filled in manually.
It said that when it identified an error it made sure conveyance solicitors corrected it, and it has never detected fraud.