I saw these statistics being used recently over at DPF's blog (by a commenter - not David) as a rebuttal that Australia's effective tax rates are lower than ours.
Evolution of the tax burden, 2000-2005
Single persons without children at 100% of average earnings
Which at first impression the table appears to show:
New Zealand 20.5%
Yay - New Zealanders rejoice; apparently our tax burden is not as bad as we feel it is... Until we read the third line of the heading which actually explains what we are looking at;
Income tax plus employee and employer contributions less cash benefits as a % of labour costs
So in actual fact the taxation burden on an EMPLOYEE shown by these figures is overstated by the rate of both compulsory superannuation (0% NZ, 9% Australia) AND contributions by employer or employee to employer run superannuation schemes. So even without assessing the final part of the distortion Australia already has a lower taxation burden than us.