The form was filled in eight months after he was caught doing 149km/h in a 50km/h zone.
Dotcom pleaded guilty under the name "Kim Schmitz" in the North Shore District Court.
Immigration NZ said yesterday it was checking on the existence of a conviction and confirmed Dotcom had not declared it.
"If any adverse information is obtained INZ will assess if there is any liability for deportation."
It also admitted it never made its own checks when it granted Dotcom residency.
The statement said Dotcom had been here for just 12 months and there was nothing to suggest he had been charged.
On Wednesday Dotcom told the Herald he believed speeding issues had been disclosed by his advisers.
Told that they had not been, he said: "Oh really? That's not good, obviously."
Immigration NZ has previously stood by its handling of Dotcom's residency, which was granted after the SIS raised concerns and after Dotcom revealed new convictions on arriving in New Zealand.
A review had been conducted and "found that the correct procedures and processes were indeed followed".
A member of the NZ Law Society immigration law committee, John McBride, said people subject to deportation would be sent to their country of origin.
Dotcom holds Finnish and German nationality so could be sent to either country.
Mr McBride said the process took more than a year if it was decided the failure to disclose the conviction warranted deportation.
The person who was under question would be asked for an explanation, with a report going to Immigration minister Michael Woodhouse.
Decisions could be appealed.
