A new estimate places the cost of a public vote on same-sex marriage in Australia at half a billion dollars.
Previous estimates for the controversial vote by the Australian Electoral Commission place the vote at a cost of AUD$158 million (£84 million).
However new estimates by PricewaterhouseCoopers (PwC), adds on some extra costs.
The modelling undertaken by the firm estimates that the plebiscite would cost the country $280 million (£150 million) in lost productivity, in addition to the actual cost of the plebiscite.
In addition, PwC says campaigns for and against equal marriage will cost Australians another $66 million (£35 million), and the cost due to the impact on the LGBT community is estimated at a further $20 million (£10.5 million).
The chief executive of PwC Australia, Luke Sayers, says the cost of the vote will be three times what was estimated by the Electoral Commission, a total of $524 million.
“Total economic costs have not been considered before and should be part of the debate on the best way to achieve a resolution to this issue,” Mr Sayers said.
Another option would be to hold the plebiscite at the same time as the general election, before next January, as it would cost much less at $113 million, or a vote in Parliament which would cost $77 million.
Other experts have pointed to campaigns in California, which cost more than $6 per voter, and is money which could be reallocated to other areas.
PwC estimates that 5 percent of the LGBT community will have negative impacts on their mental health as a result of the plebiscite and surrounding campaigns.
But local support services have, since the issue has been debated publicly, reported an increase in requests for help.
The Australian Coalition Government is facing renewed calls to call of a public vote on equal marriage.
Previous Prime Minister Tony Abbott had insisted that Coalition MPs would not have a free vote on the issue, and that a plebiscite was the only way to settle it.
However when Malcolm Turnbull took over as Prime Minister in November when Abbott was ousted, he maintained that a plebiscite would take place.
This is all despite a majority of politicians in Australia now saying they would vote in favour of legislation for equal marriage.
Meanwhile, Mr Turnbull, who is a regular attendee of Sydney Mardi Gras, last weekend became the first sitting PM to attend the festivities.