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Now is about the time many people begin the yearly chore of digging out all those receipts and other papers needed to complete their tax returns.

This can be a painful, if unavoidable, exercise. But it's also useful, as it allows us to figure out exactly just how much tax we pay.

So how highly are Australians taxed compared with people in other countries?

In short, not very. However, it's unlikely this comparatively light level of taxation can last over the longer term.

Australia was the sixth least-taxed country of the 34 members of the Organisation for Economic Co-operation and Development, latest figures show.

Total taxes revenue was worth 26 per cent of gross domestic product in 2010, compared with an OECD average ratio of 33.8 per cent.

What this means for individuals clearly varies depending on how much they earn. People who made more than $180,000 in 2011-12, for instance, pay a marginal rate of 45c in the dollar - higher than several OECD countries.

But overall, the tax burden on Australian wage earners is lower than most wealthy countries, and has been falling for the past decade.

The question is, can this last?

Until recently, we were accustomed to receiving regular income-tax cuts.

The ratio of tax to GDP fell from more than 30 per cent in 2000 to 26 per cent today, helped in part by back-to-back income-tax cuts during the Howard years and the early years of Labor's present government.

Further cuts in income tax, however, appear unlikely for now. That's because other sources of revenue are no longer growing like they used to.

The slump in house prices and sharemarkets has smashed capital gains tax revenue and the housing boom looks increasingly unlikely to return.

As well, miners are unlikely to pay huge amounts of tax any time soon because they are spending so much on new mines, which gives them big deductions.

For the longer term, the growing cost of caring for an ageing population is also likely to require more taxation, not less.

So, while today we pay relatively low levels of tax compared with other countries, this situation might not last forever.