New data published by the OECD last night shows that Australia had the biggest increase to average tax rates in the developed world last year.

Out of the 38 nations that are members of the OECD, Australia’s average tax rate increased by 7.6% in the last financial year, with a single Australian worker without kids earning an average wage were spending 24.9% of it on income tax.

Meanwhile, the average single Australian worker without kids earning two-thirds of the average wage, or $66,709, paid 20.2% in income tax — making it the highest tax burden has been for this group since 2000.

Even though wages increased for this group by around $2,500 in a year, the OECD data shows that after tax, they are only $125 better off in nominal terms — but much worse off when the effects of inflation on the cost of living is taken into account.

The reason for the increase comes down to two things: the end of a tax offset, and bracket creep.

I spent yesterday deep in the OECD’s near-700 page report taking a closer look at the data — you can read the full story below.