At the end of last year the PCO received an invoice from the man for an existing cloud-based IT subscription the office had used for a year, according to the summary of facts obtained by Open Justice.
When the bill was being paid the following month, the previously paid invoice listed a different bank account and GST number.
On further investigation it was confirmed the invoice was a fraud, and the sum of $55,200 had been paid into the account of the employee.
The man, who worked for the PCO for some time, was sentenced to 200 hours of community work and 12 months of supervision today in the Wellington District Court.
Prosecutor Morgan Speight said the man's offending was "a breach of trust in the absolute extreme" and although the man didn't do it for financial gain, he did benefit from it.
Speight said not only had the parliamentary office staff suffered, but the community as a whole had too, as the public entity had spent tens of thousands on ensuring an act like this would never happen again.
"This is not simply a case of one person taking advantage of their employer but one person taking advantage of the country as a whole," Speight said.
The man's lawyer, Val Nisbet, said his client was suffering poor mental health at the time of the offending and reparations had already been paid in full.
Nisbet said his client never took the money for financial gain, but revenge for how he claimed he had been treated in the workplace.
That alleged treatment was not outlined in court.
But according to Nisbet, the man had been going through a difficult time and said his actions were "completely out of character".
"His regret and remorse is profound... he wants to do the utmost in relationship to his own behaviour."
Nisbet said he could "virtually guarantee" his client would not come before the courts "ever again" and added that he has struggled, but learned from his experience.
"He seems to want to help other people," Nisbet said when addressing the topic of community work.
Judge Craig Thompson accepted the man's offending was a "gross breach of trust" but said pre-sentence reports outlined issues that impacted him when he chose to steal the sum.
"There were issues going on in your life that I can accept, to a point at least, affected your judgment and consciousness of the position you held."
He said the offending had come about when the man wasn't thinking straight, and a sentence of community work would give back to the community he took from.
"Given that [reparation and community work] and your clean record I can accept that this was a one-off... breach of trust that the organisation had put in you."