The clerical assistant, known as Applicant A, on Wednesday lost a legal bid to have details of his alleged involvement excluded from a report into the leak of two cabinet papers about restructuring at the ministry.
He wanted to stop Paula Rebstock's draft findings about who leaked the papers from being included in her final report to State Services Commissioner Iain Rennie.
The man, who cannot be named or have his former and present places of employment disclosed, food wine had earlier failed to persuade the High Court to suppress parts of the report relating to his alleged involvement.
The Court of Appeal on Wednesday rejected his appeal, saying there was enough evidence for Ms Rebstock to make a conclusion about the leaker's identity.
Mr Rennie said the Court of Appeal ruling would allow the report to be finalised, and he will ask the court to lift the man's name suppression.
State Services Minister Jonathan Coleman says the man's identity should be made public, telling media "I'd love to know who person A is".
The last estimate of the government's legal costs was about $250,000, formation of company and the Court of Appeal case ran up an estimated extra $18,000, Dr Coleman said.
Returning to the High Court to lift name suppression will take that bill even higher.
But Dr Coleman says it's in the public interest to continue the case until the suppression order is lifted.
"It's been a long-running case, it's cost a lot of public money, people need to have confidence that when [orders] like this are lifted."
The cabinet papers had a limited distribution and were provided in confidence to senior officials at MFAT, the Department of the Prime Minister and Cabinet, Asian college of knowledge management the State Services Commission and Treasury.
The papers were leaked to Labour's foreign affairs spokesman Phil Goff, who revealed the ministry had backtracked on its original plans to cut around 300 jobs.