Legislation has been passed moving the National Library and Archives New Zealand into the Department of Internal Affairs.
Parliament is sitting under urgency on Saturday to consider a number of bills, including the State Sector Management Bill, which has now been divided into three pieces of legislation.
One clears the way for the amalgamation of the Ministry - and Foundation - of Research, Science & Technology.
The other two deal with merging the National Library and Archives New Zealand into the Department of Internal Affairs.
Labour opposed the merger, saying it downgrades the status and independence of the National Librarian and Chief Archivist, who it says will be third-tier managers in the department.
The Government says the legislation states clearly that the Chief Archivist is to act independently, and is not subject to direction from the minister or the department's chief executive.
It also says the passing of the bill gives certainty to staff that the merger will go ahead in February.