A Prescribed Investor Rate (PIR) is the rate used to calculate how much tax you'll pay on your portfolio investment entity (PIE) taxable income. If you have KiwiSaver investments, you should do an annual check to make sure you're on the correct tax rate. If your PIR is incorrect, you might find yourself over/under paying tax for the year. Your PIR is based on your income from the last two financial years (year ended 31 March). Your KiwiSaver provider will use this rate to pay tax. Inland Revenue has an online questionnaire that you can use to help you figure out your PIR. You can check it out here.