Optimal Commodity Taxes in Australia

The recent changes to commodity taxes in Australia have led to renewed interest in a classic question in public finance: Should the tax rates be uniform or differentiated? This article attempts to answer this question by calculating optimal commodity taxes in Australia for a nine-item disaggregation. The estimates point to non-uniform commodity taxes, even from the viewpoint of an inequality-insensitive tax planner. The optimal commodity taxes bear little resemblance with the pre-GST or post-GST tax rates. No less significant is our observation that even the purely efficiency-driven optimal commodity taxes imply lower real expenditure inequality than the actual taxes.