However, Treasury will establish a new team to provide a policy costing service to the political parties, currently represented in Parliament, before the election.
Such an independent body was called for after the now-infamous "fiscal hole debate" before the 2017 election.
Associate Finance Minister James Shaw said the independent body would mean more transparency around what political parties are promising to do.
He said there would be "fewer political games played" as a result of the unit.
Treasury documents investigating the establishment of such a unit, released earlier this year, said recent elections have seen a significant focus on fiscal policy and the cost of election platforms.
A notable example of this was last election's $11.7 billion "fiscal hole" saga, where National claimed Labour's policy numbers did not add up.
Labour denied this.
With an independent costing unit, the risk of such a debate would be reduced.
"The PBO will help cut through the noise to deliver New Zealanders unbiased information during election campaigns," Shaw said.
He said New Zealand's democratic framework would be enhanced by the body.
"By levelling the playing field, meaning that political parties have access to the same resources to give the public consistent and independent information."
Robertson said he had been engaging with National and understands the party's finance spokesman, Paul Goldsmith, is consulting his caucus on the proposal.