Australian residents are taxed on their worldwide income. This page outlines the tax implications in Australia if you are working or thinking about working overseas. You will also need to take into account the tax law of the country you are working in.
If you are working overseas you need to determine whether you are still an Australian resident for tax purposes. If you are unsure, the Residency – overview can help you work out your residency status. Non-residents pay tax differently from residents on Australian-source income.