International online shopping giants appear to be shirking their responsibility to charge GST more than a week after it came into force and two years since the tax estimated to be worth $500 million a year was first announced.

UK giant Marks & Spencer, US electronics warehouse B&H and fashion retailer J.Crew are among those who have failed to add GST to their invoices, saving their Australian customers 10 per cent in tax while not disclosing their own tax obligations.

Up until July 1, GST was only paid on international purchases worth more than $1000, but that has now been extended to all online products following years of lobbying from local bricks and mortar retailers struggling against the tide of online sales.

Marks & Spencer, which has launched an aggressive campaign into the Australian market clearly states on its local invoices, “your order isn’t liable for any additional duties of import to your country".