The Government has spent $400,000 to employ the judge who is determining whether David Bain should receive compensation.
Mr Bain spent 13 years in jail over the murder of his parents and three siblings in Dunedin in 1994 and was acquitted at a retrial in 2009.
Justice Ian Binnie, a retired Canadian Supreme Court judge, was asked by the Government in November last year to consider the compensation claim.
Documents released to Radio New Zealand under the Official Information Act show that the judge has been paid almost $315,000 (excluding GST) and just under $34,000 for travel and other expenses.
It is possible the bill could rise slightly once the Ministry of Justice receives more of his receipts.
Justice Binnie has travelled to New Zealand four times over the past 11 months to talk to David Bain and others involved in the two trials.
The ministry says Justice Binnie has been paid $450 an hour, comparable to the rate paid to New Zealand Queen's Counsels when determining compensation claims.
His report has been given to the Justice Minister, who has indicated it will be released before the end of this year.