However, the FSC does concede that its proposal for preferential KiwiSaver Prescribed Investor Rates (PIR) is "but one possible way of reducing the amount lower income earners need to save to fund a comfortable retirement".
Indeed, the FSC, via a report it commissioned from economic analyst firm Infometrics, models a few scenarios.
The Infometrics report calculates effective tax rates for KiwiSaver members in a complicated way but it more or less adds an individual's marginal tax rate (because KiwiSaver contributions are after tax) to their PIR. Infometrics comes up with a range of effective KiwiSaver tax rates from 55.5 per cent, for top-earners, to 26.1 per cent for those on the minimum wage.
The reality is somewhat different. Even if you deem the existing incentive for high-income earners to invest in KiwiSaver (where returns are taxed at 28 per cent compared to the 33 per cent marginal rate) as trivial, there are, in fact, already a number of tax lurks under the bonnet. Admittedly, these lurks also apply to all Portfolio Investment Entities (PIE), of which KiwiSaver schemes are a subset.
Capital gains in most Australasian equities, for example, are tax-free in KiwiSaver PIE funds. Likewise, global equities are taxed on an assumed 5 per cent annual return, which in a good year, like last year, can result in a substantial tax-free investment filip (ignoring the flipside that the same rule can see investors being taxed on a loss).
Where KiwiSaver funds are invested, of course, can make a big difference to tax.
The Financial Markets Authority (FMA) KiwiSaver report for the 12 months to March 2013 provides a picture of the overall tax paid by members.
According to the FMA figures, the default KiwiSaver scheme sector (constrained to a maximum 25 per cent allocation to shares) paid about $33.67 million in tax on earnings of $230.7 million - or about 14.6 per cent.
Non-default KiwiSaver schemes (which have a higher allocation to shares in general), meanwhile, shelled out $101.6 million in tax on investment returns of $1.3 billion, equating to a tax rate of 7.7 per cent.
For the 12-month period all KiwiSaver schemes paid total tax of roughly $135 million on investment earnings of just over $1.5 billion - or an aggregate tax rate of 8.8 per cent.
Over the same timeframe, investment management and administration fees totaled close to $165 million, equivalent to a punishing 10.7 per cent of investment earnings.