Prime Minister Malcolm Turnbull Photo: Andrew Meares
New research suggests a stand-alone plebiscite on same-sex marriage would cost the country more than half a billion dollars.
The modelling by accounting firm PwC Australia found a compulsory vote on marriage equality would cost the Australian economy $525 million.
It estimates that a plebiscite not held on the same day as a federal election would cost the taxpayer $158 million to organise, $66 million for the community to fund the for and against campaigns and $281 million in lost productivity as people take time out to vote.
In addition, PwC Australia estimates at least $20 million in costs associated with the impact on the mental health and wellbeing of Australians.
"The real costs to government, the economy and members of the community to hold a stand-alone plebiscite are more than three times higher than the numbers commonly quoted," PwC Australia CEO Luke Sayers said in a statement.
He said the modelling showed the plebiscite would be a drain on the economy and bad for business, calling instead for a parliamentary vote as the best mechanism for change.
"It's clear from these findings that a stand-alone plebiscite on marriage equality is a massive waste of time and money that will remove focus on the economy, growth and jobs which is the real priority for Australia."
The modelling costed three parliamentary mechanisms for change on marriage equality including the stand-alone plebiscite costing $525 million.
It found that a plebiscite at the next federal election followed by a parliamentary vote would cost $113 million and a parliamentary vote involving campaigning but no plebiscite would cost only $17 million.
The PwC study found that arguments opposing marriage equality in the media and community forums would have an impact on mood disorders and the mental health of LGBTI people and become a health cost.
"This will be devastating for a segment of the community already more susceptible to mental health issues as a result of discrimination," PwC partner Suzi Russell-Gilford said.