How to connect NZ Super, KiwiSaver and a retirement income target

By GrowThenDraw Editorial Team · Updated August 10, 2026 · 13 min read · Editorial policy

A New Zealand retirement plan has at least two clocks. The first starts when paid work stops; the second starts at 65, when KiwiSaver and NZ Super are generally available. Treating those as the same date can hide a large funding gap.

This guide explains the method behind GrowThenDraw's retirement-income calculator. Every amount is expressed in today's purchasing power so the savings balances, weekly target and current NZ Super rates remain comparable. It is educational planning information, not an eligibility decision or personalised advice.

Start with the weekly life you want to fund

Begin with after-tax household spending, not a percentage of final salary. Housing, transport, food, insurance, health, family support and discretionary spending determine the target. Use a weekly number because NZ Super is commonly discussed weekly or fortnightly and because it makes the gap easier to understand.

Keep the target in today's dollars. If you want $1,000 a week of today's purchasing power, the model can hold that real target constant rather than asking you to guess a much larger nominal amount 20 years from now.

Retirement before 65 needs accessible bridge money

Suppose work stops at 60. For five years, standard NZ Super is not yet in the plan and KiwiSaver is generally still locked. Accessible investments, cash or continuing income must fund the weekly target during that bridge.

The calculator keeps accessible savings separate from the KiwiSaver amount expected at 65. It solves the bridge under the entered real return and other income. If accessible savings run out at 63, a future KiwiSaver balance cannot retroactively cover the missed spending at 63.

Use the correct 2026 NZ Super line

Work and Income's rates from 1 April 2026 distinguish a single person living alone, a single person sharing, a couple where both qualify and a couple where only one qualifies. It then lists the gross rate and after-tax rates under M, S, SH, ST and SA codes.

For example, the standard M-code amount is $1,110.30 a fortnight for a single person living alone. Where both partners qualify, the combined M-code amount is $1,708.16 a fortnight. Those are not interchangeable household amounts.

NZ Super is taxable. Other income can change the appropriate tax code and therefore the amount deposited. Overseas pensions can also affect NZ Super. Select the planning line that matches the current official table, then confirm the real outcome with Work and Income and Inland Revenue.

Enter KiwiSaver at 65 in today's dollars

A KiwiSaver projection may show a future-dollar balance and an inflation-adjusted balance. Use the inflation-adjusted result in a today's-dollar retirement-income plan. Putting a nominal $700,000 future balance beside a $1,000 current weekly budget would overstate what the balance can buy.

If retirement is later than 65, the calculator grows the entered age-65 KiwiSaver value to the later retirement age using the selected real return. If retirement is earlier, it adds the entered KiwiSaver amount only at 65.

Translate the target into two portfolio gaps

Before 65, the annual portfolio gap is the annual spending target minus other after-tax income. From 65, the annual gap is the target minus other income and the selected after-tax NZ Super amount. Only a positive remainder needs to be drawn from savings.

If income is above the target, GrowThenDraw reports the surplus but does not silently invest it. Reinvestment is a separate decision and assuming it automatically could make the displayed plan look safer than the visitor intended.

Use a real return, then test a lower one

A real return is the investment return after fees, tax and inflation. Sorted documents a 3.5% net-return and 2% inflation assumption for its retirement calculator, equivalent to roughly 1.5% a year in real terms. GrowThenDraw uses 1.5% only as an editable starting point.

The expected case compounds a smooth real return monthly after each modelled monthly withdrawal. Real markets do not arrive smoothly. A poor return early in retirement can do more damage than the same average return arriving later, so a lower-return scenario is a minimum stress test rather than proof of safety.

Read the required-savings solver correctly

The solver finds the accessible savings needed when work stops so the entered weekly target has no modelled shortfall through the chosen end age. It accounts for the future KiwiSaver addition, other income, the selected NZ Super rate and the expected real return.

A result is conditional, not a guarantee. It does not include random market sequences, aged-care costs, changing housing costs, provider withdrawal restrictions, future tax changes, a bequest target or a change to NZ Super policy. The sustainable weekly figure is the same type of conditional result: the highest constant target that survives the smooth expected-return scenario.

A worked bridge example

A person plans to stop work at 60, spend $1,000 a week and receive $200 a week of other after-tax income. With a 0% real return, the five-year pre-65 gap is $800 × 52 × 5, or $208,000. That amount must be accessible at 60; it is separate from KiwiSaver arriving at 65.

From 65, if the person receives the single-living-alone M-code NZ Super rate of $555.15 a week and the $200 other income continues, savings need to provide about $244.85 a week. The model then tests that draw against the age-65 KiwiSaver balance and remaining accessible savings through the selected end age.