(3c) Estimates of GST revenue receipts fluctuate throughout the year subject to regular determinations by the Australian Taxation Office (ATO) of the expected size of the GST revenue pool and by the ABS of the total Australian population and corresponding State shares. Any variations between budget estimates and actual outcomes are a result of these determinations.

It must be noted that there have also been significant trade offs in own source tax revenues. This means the change from published estimates to actual outcomes does not necessarily mean a windfall.

(4) Estimates for the out-years (i.e. those beyond the Commonwealth's three forward years) are derived from a model developed by the South Australian Treasury. At the time of signing the Intergovernmental Agreement on the Reform of Commonwealth State Financial Relations (IGA) the States agreed that South Australia would develop and maintain the model on behalf of all States to ensure a level of consistency across all jurisdictions. It should be noted, however, that jurisdictions are not restricted to using these estimates for their own budgetary purposes.

(5) Out-year estimates are subject to the Commission's annual recommendation to the Federal Treasurer of State GST revenue sharing relativities and determinations by the ATO and ABS, with regards to expected GST revenue collections and the size of the Australian population.