Younger Australians are driving the spending on overseas ­fashion websites, with 61 per cent of ­respondents aged 18-24 saying that they had bought a fashion item on an overseas website this year.

Cheaper prices are the biggest influence, with 41 per cent saying price was the deciding factor.

A further 33 per cent said they would buy from an overseas site when the product was not available locally.

The manager of Adelaide’s The Birdcage Boutique, Kat Daly, said it was easy for customers to expres­s purchase online if a size was not available in-store.

“It makes sense for inter­national online retailers to have to pay GST,” Ms Daly said. “If they don’t, we are not competing in an even marketplace.”

Birdcage’s online manager, Sinizi Peters, said the biggest part of its trade was through its online store, which received a lot of traffic from New Zealand, the US, Singapore, Europe and the Cayman ­Islands.

“At the moment we’re revamping to a whole new website, to update more collections and include a new fashion blog,” Ms Peters said.

“People find the store because of our social media avenues, whether it be Instagram, Pinterest, Twitter or Snapchat.

“It is important that we keep publishing our latest looks.”

The owner of Adelaide cycling store Mega Bike, Claud Altin, is a strong campaigner for the GST to be applied to items brought from overseas websites.

He said the current state of play was killing stores and was making a mockery of Customs. “Bricks-and-mortar stores are working harder than ever before,” Mr Altin said.

“Not only do we sell to the community — and have the highest level of knowledge on our stock — but we are also coaching and teaching over 100 people every week.

“We are growing the marketplace, but the success isn’t coming back to us.”

Mr Altin said the world’s biggest supplier of bike parts enjoyed a $200m share of the Australian market, and was growing, yet was not paying tax on sales.

Andrew Clarke, the chief executive of Australia-based website Cashrewards, said the country was in the midst of an “evolution” in the shopping industry, driven by a consumer search for better prices­, greater incentives and ­rewards on demand.

“While our local retailers can’t always compete on price or ­product range ... an area of customer service that local retailers could innovate to win Aussies back — and which overseas ­retailers would struggle to offer — is on delivery,” he said.

“If Aussies receive outstanding service in the delivery stage of the shopping cycle, I believe our local spending will increase.”

A spokesman for Scott Morrison said the Turnbull government was proceeding with the plan to apply the GST to ­digital products and services and had prepared updated draft legislation.

The government hoped to apply the GST from July 2017 to level the playing field so that tax would no longer be a factor for a consumer in deciding where to buy goods or services.

It is understood the tax on the sale of overseas-supplied digital goods might be collected from so-called “marketplace aggregators” such as Google Plus rather than from suppliers themselves.