NZ’s GST is certainly the most efficient form of VAT in the world.
The “VAT Revenue Ratio” is used by the OECD as a measure of VAT efficiency. The average in the OECD is about 50%.
The least efficient is Turkey’s VAT at about 30%. NZ ranks top at a little more than 95%, followed closely by Luxembourg.
Australia’s VAT Revenue Ratio is around 45%.
The Australian Treasury Secretary thinks they can learn from NZ’s GST and argues for a further shift in Australia from income taxes to GST. See: http://www.stuff.co.nz/business/world/9900014/Aussies-should-follow-our-GST-lead
If efficiency is the goal then the evidence seems compellingly in favour of the Secretary’s argument.
However, political realities seem to pull most countries in the opposite direction.
Yes VAT is spreading around the world as the tax of choice for governments but, increasingly those governments are voting for multiple rates, exemptions and zero rating when designing their version of VAT.
When the GFC hit we saw governments making greater use of reduced rates to stimulate activitiy. There is now a growing trend to use penal VAT rates as policy tools to discourage certain “undesirable” consumption (e.g for environmental reasons). Policies like these make a VAT system less efficient but they also make it more politically acceptable and relevant.
Perhaps the questions are: how long can NZ resist these political pressures and is it more likely we will follow the Aussie lead?