There doesn't seem to be anything particularly difficult about taxing capital gains.

The ability to tax “deemed income” already exists thanks to the FIF regime – just needs a little tweaking.

You can only tax things which you can easily and readily value. Helpfully there are share registries, rating databases, tax returns, company filings, and the like which allow a valuation to be made and a loss/gain calculated relatively simply.

And of course, the exceptions/exemptions. Helpfully there are many countries with a CGT with exceptions/exemptions, so it’s not a major exercise to pinch an idea or two (or four or more) to suit New Zealand’s undoubtedly “special and unique conditions”.

As with GST, a fairly long period for the Great New Zealand Public to warm to the idea, and a small legion of comms people to sell the idea and the details.

Then you’d need a start date for the valuations – ideally a couple of years in the future.

Administratively it’s not particularly difficult – the source data pretty much already exists, making it an integration exercise as much as anything. Set it up and just wait for the transactions to start ticking over and the money to start rolling in.

And who would you get to do it?

Who better than the Tax Partners at EY, Deloittes or some crowd like that. Pay them five million bucks a head for the detailed design, two new passports in names of their choosing, and a complimentary one-way ticket to anywhere else in the world. And a five million buck bonus payable after three years if it rakes in as much as their design predicted.