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The personal income tax cuts delivered by the Howard and Rudd governments may be the last for a decade with an analysis showing huge long-term gaps in the Commonwealth's finances.

A study released by Treasury pinpoints those tax cuts and others by prime ministers John Howard and Kevin Rudd, changes in the spending patterns of ordinary Australians and the rise of the mining sector as reasons there will simply not be enough money for Canberra to promise more tax relief.

Compiled by tax experts John Clark and Adam Hollis, the study looked at Australia's tax-to-GDP ratio. It peaked at 24.2 per cent in 2004-05 but crashed in the wake of the global financial crisis.

And even with the economy on the mend it is still short of its long-term average.

The authors identified a series of issues that have hit tax collections, starting with deep cuts in personal income tax started by Mr Howard and continued by Mr Rudd.

The full impact of tax bracket creep won't wash through the Government's finances for some time. Another issue has been the rise of the mining sector and the relative decline of others.

The authors note that while the mining sector faces the same 30 per cent company tax rate as other industries it has access to deductions, particularly for capital and State royalties, not used by sectors such as retail.

Capital gains tax, hit hard by the global financial crisis, continues to be a problem for the Budget. If it had stayed true to trend estimates over time, capital gains tax receipts would be $5 billion higher this year.

And if capital gains had stayed around the levels recorded in 2007-08 the Federal Budget would be $17 billion better off.

The effect of Mr Howard's decision to freeze the indexation of excise on petrol continues to haunt treasurers.

Fuel excise would be $6.7 billion higher today if indexation had been left in place and by 2016-17 the shortfall is forecast to reach $8.4 billion.