The Tiwi Island Sistagirls say the upcoming same-sex marriage postal vote could be a waste of time in their community because people there are not familiar with the process.

"I think it's rubbish really, they're just wasting their time," said Sistagirl Shaun Kerinaiua.

"Most of our people don't speak English, it's our second language and that goes for all Aboriginal people in Australia."

The Sistagirls are a group of transgender women from the Tiwi Islands.

An estimated $122 million will be spent on a statistical survey of the nation, which will be conducted by the Australian Bureau of Statistics to gauge public interest in changing Australia's Marriage Act to allow same-sex couples to marry.

"The Government doesn't understand, the Government thinks that Aboriginal people are going to understand," said Sistagirl Crystal Johnson.

"We speak eight, nine, 10 different languages and there are Indigenous people who don't speak English.

"The money should be going to bring the information [about the vote] to our people in a way that Indigenous people can understand."

Crystal Johnson (L) and Shaun Kerinaiua believe the same-sex marriage vote could be a waste of time on the Tiwi Islands. ( ABC News: Dijana Damjanovic )

The Government has given people until August 24 to ensure they are eligible to participate in the optional postal vote through the Australian Electoral Commission.

"It's a bit frustrating that there is a website that needs to be used to register — a lot of our people are not literate, we are not up to standard education-wise, I think it's all just horrible," said Shaun Kerinaiua.

It is estimated around $66 million will be spent funding the Yes and No campaigns, according to PwC Australia.

On Tiwi, the Sistagirls will be working with limited resources to inspire a yes vote in their community.

"Crystal, myself and some of the other girls will have a rally, [we'll] put some signs up, hold group discussions and some family gatherings to spread that news and the awareness," said Shaun Kerinaiua.

Earlier this year, the Sistagirls travelled to Sydney for their first Mardi Gras. ( Twitter: @mrbenjaminlaw )

"We have an interpreter's services [in the Northern Territory] and we have some people who are well spoken and well educated and hopefully they can get out to community members and have translation from English to whatever language they speak."

Tiwi Islanders are familiar with the process of polling during federal and local elections, and the Sistagirls believe the vote on same-sex marriage would be more successful if it were held that way.

"[People in our community] have to go and vote if they want a new prime minister, so I think I think they should keep [the vote on same-sex marriage] simple, especially for the remote communities," said Shaun Kerinaiua.

Despite the barriers, there is hope among the Sistagirls for a positive outcome.