How is child support calculated in New Zealand?

Inland Revenue uses a formula based on both parents' incomes, the number and age of children, and how many nights each parent cares for them. Each parent has a living allowance deducted first. The parent who earns more relative to their share of care generally pays the other. This tool gives a simplified estimate of that idea.

How accurate is this estimate?

It is indicative only. The official formula uses set living allowances, a care cost table, and an age based child expenditure table that change each year. For an exact assessment, use Inland Revenue's own estimator or contact them directly.

Does shared care change child support?

Yes. The more nights you care for the children, the more of their costs you already meet directly, so your child support liability falls. When care and income are both shared evenly, payments can be small or nil.

Child Support Calculator

This calculator gives you an indicative estimate of child support in New Zealand, using a simplified version of the income and care formula Inland Revenue applies between separated parents. You enter your own annual income, the other parent's annual income, the number of children, how many nights a year you care for them, and an editable living allowance deducted from each parent's income before the calculation runs. From those figures, it works out each parent's share of the combined child support income, compares that with each parent's share of care, then applies an age based cost percentage that rises with the number of children to estimate who pays whom. The result shows the estimated amount payable or receivable per year, broken down into a monthly and a weekly figure, so you can see what it means for your regular budget. More nights of care lower what you pay, because you already cover more of the day to day costs directly, and a change in either income shifts the balance too. Because the real Inland Revenue formula uses set living allowances, a care cost table and an age based expenditure table updated each year, treat this as a guide only, not an official assessment. Use it to see how income and care nights move the numbers, then check the exact figure with Inland Revenue's own estimator before relying on it.

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This is a simplified estimate. The official Inland Revenue formula uses set living allowances and care and expenditure tables that change each year. Use IRD's estimator for an exact assessment.

Your income

Other parent's income

Number of children

Your nights of care (per year)

Living allowance each (editable)

estimated child support you would pay per year

Per month$0

Per week$0

How the estimate works

Each parent's child support income is their income less a living allowance. The parents' shares of the combined child support income are compared with their shares of care. The parent whose income share is higher than their care share pays the other, based on an estimated cost of raising the children. More nights of care lowers what you pay because you are already meeting more of the cost directly.

Why use the IRD figure

The official formula sets the living allowance, the care cost percentages, and the cost of children by age and combined income, and these are updated each year. Those details move the result, so treat this as a starting point and confirm with Inland Revenue before relying on a number.

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Working for Families Calculator: family tax credits.
Budget Calculator: plan around payments.
PAYE Calculator: take-home pay.
Disposable Income Calculator: income after costs.

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Reviewed and maintained. Last reviewed 2026-07-02 and checked on a twice-monthly cycle against IRD, RBNZ and Stats NZ. How we keep data current.