Until a new government is formed, the previous National Government continues in a caretaker role.
It can deal with administrative and minor issues but is restricted from making significant decisions or appointments. By convention these are left to the incoming Government.
It is important this time because election night did not deliver a clear-cut result for the first time since 2005.
National's Steven Joyce said he had no intention of bucking the convention. The caretaker period meant keeping up with the normal "machinery of government", he said.
The Cabinet Manual says caretaker governments can implement decisions already made, but cannot decide on controversial issues, issues with long-term impact such as major contracts or significant appointments, or changes to policy.
The situation will continue until at least October 7, when the final vote count is completed. There were a record 384,000 special votes. They include any cast by voters who enrolled within two weeks of election day, voters on the unpublished roll, votes cast from outside a person's electorate or from overseas, and those that used the telephone dictation service.
These take longer to verify, particularly those where the voters had only just enrolled.
In addition, the election night totals were preliminary results. The official results process started the next day, with all 2,180,000 votes rechecked.
The left bloc could pick up one or two seats from the special votes, while National could drop one to two.