The man who oversees the nation's finances insists holding a $122 million voluntary postal ballot on same-sex marriage is money well spent.
Treasurer Scott Morrison was out on Thursday morning defending the government's decision to hold a non-binding vote.
The coalition is keeping the plebiscite commitment it took to the 2016 election, he said.
"We had this debate at the last election. The government was returned on the basis of many things (including) our economic management," he told the Seven Network.
When pressed on the cost of the postal ballot, Mr Morrison said: "Keeping promises is money well spent."