The reasons behind the High Court's decision to give the same-sex marriage postal survey the green light will be made public.
The full bench's written judgment is due to be published on Thursday, three weeks after the ruling was made.
It found the finance minister did have the power to fund the $122 million voluntary survey in the way he did, allowing forms to be mailed from September 12 as planned.
Two groups of same-sex marriage advocates tried to stop the postal survey, arguing the government should not have bypassed parliament in funding it.
The court unanimously dismissed the first challenge by a group of advocates led by independent MP Andrew Wilkie.
A second challenge led by Australian Marriage Equality was dealt with but the High Court declared the finance minister's determination was not invalid and he did have the authorisation to make it.
The voluntary survey was the government's plan B after the Senate blocked the compulsory plebiscite promised by the coalition at the 2016 election.
The survey closes on November 7, with results to be published on November 15.
