"But I never got a receipt."
The offending came to light when the department discovered processes for cash receipts were not being followed.
During the department's investigation, officers would visit the applicant and question him about whether he had paid the fee.
Ranginui put his family's citizenship in jeopardy, and they thought they would have to find the money again to pay, the man said.
The man and his family had since been granted citizenship, but he said he had lost trust in government departments. "I will never pay cash to them again".
The department's Births Deaths and Marriages Registrar-General Jeff Montgomery said they relied on the integrity of all staff.
"We expect our staff to meet a very high standard. Mr Ranginui's role was one that involved a special relationship of trust.
"Mr Ranginui abused this trust. The staff of the Citizenship Office feel extremely let down and betrayed."
Systems that had been put in place to catch illegal behaviour of staff had "worked well", he said.
"In the rare occasions where [illegal actions] may occur we have systems in place to quickly identify it and prosecute the offender."
Judge Moss said there was "significant public interest [in the case] because of New Zealand's proud record of incorruptible public servants".
Ranginui relied on a good rapport he developed with the migrants who were applying for citizenship, she said.
His victims "quite rightly" did not have to pay the fee again, but it was still a large amount of money taken, she said.
Ranginui's lawyer Craig Foster said his client was "very remorseful" about the offending and was motivated to rehabilitate himself.
"He is motivated to address the underlying issues behind his offending."
He had already paid a price of losing his job because of the thefts, Mr Foster said.
Judge Moss sentenced Ranginui to 250 hours of community work and supervision for six months, which would give him time to undertake a gambling addiction course.
He was also ordered to pay reparation of $3526.70 -- the amount of money he stole.