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Herald writer Brian Fallow says that the biggest problem the tax system faces, "is that in a globalised era we are taxing all the wrong things."

He suggests scrapping the provision exempting mortgage payments and rents from GST.

"More than 40 per cent of the income tax - much the biggest single source of Government revenue - comes from the top 10 per cent of taxpayers ranked by income, which is dangerous when labour is as mobile as it is and the income gap with Australia and most other developed countries is as large as it is."

Should GST be added to rents and mortgages?