New Zealanders are being warned to watch out for fake websites and social media accounts claiming to be represent the official Census.
CERT NZ's director Rob Pope said scammers were using the oppurtunity to harvest information and sometimes to defraud people of money.
Stats NZ's deputy chief executive Census and Collection Operations, Simon Mason, said it did not send any unsolicited messages or private messages through social media.
Mason said officials had already spotted and removed fake accounts immitating Stats NZ's official Twitter account.
He was asking people to stay vigilant ahead of Census Day tomorrow, and to report any suspicious accounts to CERT NZ.
Mason said after Census day Stats NZ would be following up with households who did not complete their census forms.
There would be an extension until June for people in communities affected by Cyclone Gabrielle, he said.