RWT is the acronym for Resident Withholding Tax. It is provided by you on account creation. It is the tax rate at which interest earned on savings is deducted, the same as for any bank interest or dividend on direct investments are taxed. Your RWT rate is your assessment of the right marginal tax rate for income tax. If you get it wrong, you will have tax to pay or a refund due in your tax return. If you significantly underestimate there may also be penalties from Inland Revenue.
By contrast, any investment income in Kernel Funds are taxed at your PIE rate, which are calculated differently to a maximum of 28%. There is no capital gains tax in New Zealand.
See more at https://kernelwealth.zendesk.com/hc/en-us/articles/360025598873-What-is-a-Prescribed-Investor-Rate-PIR.
To change your RWT rate, please email firstname.lastname@example.org and we will change it for future tax calculations. We cannot refund over deducted tax, only Inland Revenue can do this as part of a tax return.