Just because they can do that, doesn't make it right, especially when the services are provided in Australia (such as advertising on Google's sites, delivered via Google's equipment in Australia, as one example of many), and it's only the billing which is handled in Ireland, which it most definitely is in the case with Google. I'm not a mathematical genius, but the standard company tax rate in Australia is 30% - and when the ATO can see $1 billion of declared payments (including GST) to Google, and then a total payment of tax of less than 0.0007 of that income earned in Australia, they are right to ask questions. Google's laywers and accountants are taking the piss out of the ATO by avoiding to this extent.