Tribunal chairman David Plunkett saiddelegating work exclusively reserved under the act to licensed immigration advisers "is serious" and a caution would not reflect the seriousness of Singh's conduct.
"Both Mr Singh and the unlicensed staff member of the recruiting company in the Philippines may have committed statutory offences," Plunkett said.
"It is not my role to assess whether the conduct is criminal, but the possibility shows the seriousness of the professional violations."
He said this was in a sense an isolated incident which arose from one set of instruction and one critical mistake by Singh.
Singh had received a warning from Immigration NZ before it filed a complaint to the Immigration Advisers Authority.
INZ said Singh had attempted to mislead the agency by relying on unlicensed persons to provide advice to his clients and having no contact with them himself.
The complaint was then referred to the tribunal on November 21, 2017, alleging Singh had breached the Licensed Immigration Advisers Code of Conduct.
In upholding the complaint, Plunkett found Singh "was unprofessional and failed to exercise due care in permitting an unlicensed person to provide immigration services that only a licensed person is permitted to do".
He said there was no doubt that all three clients would have asked the unlicensed agent about prospects of converting the work visas to residence visas.
At least two of them have now sought residence, and two are married and were likely to have asked for advice on how to get their families to New Zealand.
"The behaviour of Mr Singh crosses the disciplinary threshold by a demonstrable margin," Plunkett had said in an earlier decision.