The bank takes it out at a standard rate - when you open an account you tell them your marginal rate, if you get it wrong it's obvious to the IRD. We have no t

The bank takes it out at a standard rate - when you open an account you tell them your marginal rate, if you get it wrong it's obvious to the IRD. We have no tax on capital gains (we should, it badly distorts our markets, leaves too much money in real-estate).