Compound Interest Calculator - PIE vs Non-PIE Tax
This calculator shows how much your tax structure affects long-term investment growth, comparing what the same investment would be worth if held in a Portfolio Investment Entity (PIE) fund taxed at your Prescribed Investor Rate (PIR) versus a non-PIE investment like a term deposit taxed at your full marginal rate. You enter your initial lump sum, a regular monthly contribution, your expected annual gross return rate, how many years you plan to invest for, and how often returns compound (monthly, quarterly, annually or daily). You then select your PIR, capped at 28% regardless of income, and your marginal tax rate, up to 39%. The calculator runs the same growth assumptions through three scenarios and returns your total contributions, your PIE final balance, your non-PIE final balance and the total tax saving from using a PIE structure, alongside a full breakdown of gross returns earned and tax paid in each case, a balance-over-time chart and an optional year-by-year table. Because the extra amount saved on tax each year keeps earning returns of its own, even a small PIR advantage compounds into a meaningfully larger balance over a long investment horizon. Use it to see whether your KiwiSaver, managed fund or savings sit in the most tax-efficient structure for your income. Results are estimates based on constant assumed returns and are indicative only, not financial advice.
See the PIE tax advantage on your investments
Enter your investment amount, return rate, and tax rates to compare PIE vs non-PIE after-tax growth
PIE Funds and the Prescribed Investor Rate Explained
A Portfolio Investment Entity (PIE) is a type of managed investment fund registered with IRD in New Zealand that qualifies for special tax treatment. Instead of investment returns being added to your personal income and taxed at your marginal rate, returns inside a PIE fund are taxed at your Prescribed Investor Rate (PIR). The critical feature of PIR tax: it is capped at 28%, regardless of how high your income is.
This means a person earning $150,000 per year who would normally pay 33% tax on investment returns pays only 28% on returns within a PIE fund. A person earning $250,000 who would normally pay 39% pays only 28%. The tax is deducted from returns by the fund manager before distributions, so there is no additional personal income tax return required for PIE income and no top-up tax at year end.
How to Work Out Your PIR
Your PIR is determined by your taxable income in each of the past two income years, using both a taxable income test and a combined income test (taxable plus PIE income). Take the lower rate from the two years. The rates are: 10.5% if taxable income was $15,600 or less and combined income was $53,500 or less; 17.5% if taxable income was $53,500 or less and combined income was $78,100 or less; 28% otherwise.
You tell your PIE fund provider your PIR when you invest. If you use a rate that is too low, IRD can require you to pay the difference. If you use a rate that is too high, the overpaid tax is not refunded - it is a permanent cost. Getting your PIR right matters, and if your income changes significantly, you should update your PIR with your provider.
Why the PIE Tax Advantage Compounds
The difference between a 28% PIR and a 33% or 39% marginal rate seems small in year one. On $10,000 of returns at 6%, the difference between 28% and 33% tax is $50. But because the after-tax balance is different, the following year's returns are calculated on a larger base in the PIE scenario. This is the compounding tax advantage: the money saved on tax in year one earns returns in year two, and those additional returns earn returns in year three, and so on.
Over a 20-year horizon on a $50,000 investment growing at 6% with $500 monthly contributions, the difference between a 28% PIR and a 33% marginal rate typically exceeds $20,000 in final balance. The difference between 28% PIR and 39% marginal rate can exceed $40,000. These are not trivial amounts, and they explain why PIE-structured managed funds and KiwiSaver accounts are consistently preferred over non-PIE alternatives for New Zealand investors in higher income brackets.
KiwiSaver as a PIE Fund
All KiwiSaver schemes are PIE funds. This means your KiwiSaver returns are automatically taxed at your PIR, not your marginal rate. For many New Zealanders, this is the largest single pool of PIE-structured investment they hold. The PIR tax is applied within the fund - you do not receive a separate invoice from IRD for KiwiSaver returns, and the tax does not appear on your end-of-year income tax assessment.
Because KiwiSaver also receives employer contributions and the government member tax credit (up to $260.72 per year on qualifying contributions of $1,042.86 or more), it combines the PIE tax advantage with additional return boosts unavailable to other investment structures. For most employed New Zealanders, maximising KiwiSaver to capture the full employer contribution is the highest-return first step before considering other investments.
Non-PIE Investments: Term Deposits, Savings Accounts, and Direct Shares
Interest earned on term deposits and savings accounts is non-PIE income. It is added to your taxable income for the year and taxed at your full marginal rate, which can be up to 39%. Dividends from NZ shares are treated differently (they carry imputation credits), but foreign share income is subject to the FIF regime for significant holdings. These non-PIE treatments mean that for higher-income investors, holding liquid savings in a PIE cash fund rather than a bank term deposit can meaningfully improve the after-tax return on the same underlying interest rate.
Many PIE-structured cash funds offer returns very close to term deposit rates while providing the PIR tax treatment. For a 33% taxpayer, a PIE cash fund at 4.5% gross effectively beats a term deposit at 4.5% gross because the PIE is taxed at 28% while the term deposit is taxed at 33%. The equivalent term deposit rate that would produce the same after-tax return as the PIE fund is approximately 4.5% multiplied by (1 minus the PIR) divided by (1 minus the marginal rate).
Frequently Asked Questions
What is the PIR rate for most KiwiSaver members in New Zealand?
Most employed New Zealanders earning more than $53,500 per year have a PIR of 28%. This is the most common PIR for working-age KiwiSaver members. The 28% cap means even high earners benefit from a reduced rate compared to their marginal rate of 33% or 39%. New Zealand residents on lower incomes may qualify for 17.5% or 10.5% PIR, which provides an even larger tax saving relative to the non-PIE treatment.
Is PIE tax paid upfront or at the end of the year?
PIE tax is generally deducted by the fund manager from your returns on a regular basis, often quarterly or at the time of withdrawal. For most managed PIE funds, tax is accounted for within the unit price of the fund. This means your stated balance already reflects the after-tax position - unlike non-PIE investments where returns are gross and you pay the tax later through your tax return or end-of-year assessment.
Can I have both PIE and non-PIE investments?
Yes. Many investors hold KiwiSaver as their primary PIE investment alongside term deposits, shares, or other non-PIE assets. The tax treatment applies per investment type. Calculating the after-tax return for each allows you to compare like for like and allocate savings to the most tax-efficient structure first.
What happens if I set my PIR too low?
If you use a PIR that is lower than your correct rate, IRD will require you to pay the additional tax owed, along with possible use-of-money interest. Your provider is required to use the PIR you provide, and they are not responsible for checking it is correct. You should review your PIR whenever your income changes significantly - for example, after a promotion, starting a second job, or moving into self-employment.
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