As Finance Minister Arun Jaitley is not well and undergoing treatment for diabetes management, Sitharaman would represent the country at the meeting to be held at Cairns on September 20-21, sources said.
Among other things, G-20, a group of developed and developing nations, is likely to discuss automatic sharing of tax information.
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Amid an increasing number of tax avoidance cases, India and other economies have been pressing for effective system for getting financial information from other nations, especially low tax jurisdictions.
The G-20 minsters are also likely to deliberate on concrete steps to push global GDP by an additional 2 per cent by 2018.
The meeting will be followed by a summit to be held at Brisbane in November. Prime Minister Narendra Modi is expected to attend the summit.
The G20 membership represents about two-thirds of the world's population, 85 per cent of global gross domestic product and over 75 per cent of global trade.
The members are Argentina, Australia, Brazil, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Republic of Korea, Mexico, Russia, Saudi Arabia, South Africa, Turkey, the UK, the US and the European Union.