I'd have to recommend using an accountant. The whole thing is vastly complex for a start and appears to work generally along the lines of the IRD decide whatever they want is the case in any grey area - inevitably to their benefit not yours. If you disagree, feel free to go to the expense of taking them to court....with their in-house legal team and tax payer funded bottomless pit of money for paying QC's....!

 

At least if you are following the advice of a proper accountant, and it turns out to be wrong, they are less likely to try and penalise you as a tax evader (note - less likely, not won't!).

 

Also recommended is insurance against the cost of being audited. Most accountants offer that and we have it. Costs around $300 a year I think and means that accountancy and legal fees incurred if the IRD decide to audit you are mostly paid by the insurer. Since they could easily run into the tens of thousands of dollars in a big audit, the modest annual premium is well worth it IMV. YMMV of course.