If you use digital currencies (such as Bitcoin) in your business, you have had to pay GST twice: once on the purchase of the digital currency and once again when using digital currency to purchase anything already subject to GST.
Recent law changes mean that as of 1 July 2017, purchases of digital currency are no longer subject to GST.
This means that sales and purchases of digital currency have no GST implications. Using digital currency to pay for purchases of goods and services is the same as using money.
Courtesy: ATO Small business newsroom