Australia is missing out on the kind of economic windfall that will result from same-sex marriages in New York, according to Australian marriage equality advocates.

From Sunday evening Sydney time officials in New York will begin marrying same-sex couples. Australian Marriage Equality, National Convener, Alex Greenwich, said, "The most conservative estimate is that marriage equality in New York will generate at least $225 million over three years, including marriage license revenue of $25 million for the state government, but some economists put the figure as high as $1 billion a year for the next three years."

"With a similar sized population and economy Australia is clearly missing out on a huge windfall by not allowing same-sex marriages."

"If we multiply the number of Australian same-sex couples who say they will marry with the average Australian wedding spend we get a figure of about $700 million including almost $20 to $30 million for state governments in the form of marriage license fees."

"That doesn't include the economic impact of couples travelling to Australia to marry and honeymoon, or the obvious appeal this reform will have to the global creative class."

Australian same-sex partners planning to wed in New York say their excitement is tinged by the sadness of knowing their marriage will not be recognised in Australia.

Lauren and Suzanne, who will wed in New York in September after winning a competition run by NOVA FM to send one lucky same-sex couple to the Big Apple to marry, said they are excited about their New York wedding but long for the day their solemn vows will be recognised in Australia.

"We cannot wait to get married in New York, and hope one day soon our love will be recognised equally here in Australia", Lauren said.

Simone Petersen, an Australian ex-pat living in New York City, said she and partner intend to marry as soon as possible.

"By Monday morning there will be hundreds of same-sex couples married in New York without any of the dire predictions of the opponents of equality coming true", Simone said.

"These couples and their families will enjoy all the benefits of legal equality and equal social recognition, New York state will be a more equitable place to live, and the sky will not have fallen in."

The Australian Government does not allow same-sex couples to marry in Australia and refuses to recognise overseas same-sex marriages.

In 2010 Tasmania became the first Australian state to recognise overseas same-sex marriages as state civil partnerships.

The UCLA Law School's Williams Institute has estimated the economic benefit of marriage equality to New York state at $225 million over three years.

The Independent Democratic Conference puts the figure at just over $300 million, while other estimates go as high as $1 billion per year for three years.

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