BillyAnderson:
It's always good to check such things, but with such disgustingly pathetic interest rates at the moment 😢 you'd have to have a very very large amount of money invested to lose more than a few dollars anyway.
An important point in respect of the opening post is that, if you get charged a high rate of RWT by your bank, you’re not losing any money - it’s just a timing issue and a ‘use of money’ issue. It all gets sorted out at the end of the tax year and you’ll either get a correspondingly higher refund from IRD (or pay less terminal tax then you otherwise would have). The point is, who wants the government to have the use of your money during the year - better to have it in your own pocket.
Similarly if you accidentally or deliberately understate your RWT rate, the converse applies - you’ll pay the the missing amount to IRD at the end of the year.
Tax deducted under the PIE/PIR regime doesn’t get sorted at the end of the year. Interest on PIE investments doesn’t get included in your tax return - it’s ‘full and final’ when deducted at source.