I think the whole RAR thing is very misleading!
Unless you are a professional investor who can claim write offs as a deductible expense then you are paying tax on a much higher value than your "profit"
In this situation ones return is lower than the calculated RAR.
The IRD needs to get a kick up the ass and hurry up changing the way it views such an investment where there are expected losses of capital and then Harmoney could allow for it in their tax withholding.