Child Support
Child support is a formula-based payment scheme administered by Inland Revenue under the Child Support Act 1991, requiring separated parents to contribute to the cost of raising their children based on income and care arrangements, rather than a court-set amount. Each parent's income is first reduced by a flat living allowance ($30,557 for 2026-27, up from $29,909 for 2025-26; a higher $34,252 applies if the parent receives a supported living payment) and by an allowance for any other dependent children they support, giving each parent's child support income.
The cost of the children themselves is then estimated from IRD's published child expenditure tables, which scale with the parents' combined child support income, the number of children, and their ages (0–12 versus 13+). Each parent's share of that cost is based on their share of combined income, then offset by the percentage of nights they care for the children — more nights of care reduces what a parent owes (or increases what they receive).
A statutory minimum annual rate ($1,211 for 2026-27, up from $1,175 for 2025-26) applies to whichever parent is assessed as the payer, so that a minimal liability still results in some payment. Parents can apply through myIR, and either parent can request a formula assessment even without agreement from the other.
How it works
The formula assessment starts by working out each parent's child support income: their taxable income for the relevant period, less the flat living allowance ($30,557 for 2026-27, up from $29,909 for 2025-26, or the higher $34,252 rate for a parent on a supported living payment), and less any allowance for other dependent children they support. This step recognises that a parent needs to cover their own basic living costs and any other children before contributing to the children being assessed.
IRD then estimates the actual cost of raising the children using its published child expenditure tables, which scale with the parents' COMBINED child support income, the number of children involved, and whether each child is under 13 or 13 and over (older children cost more to raise under the tables). Each parent's dollar share of that total cost is based on their proportion of the combined child support income, then reduced by the percentage of nights they personally care for the children — more nights of care lowers what a parent pays, or increases what they receive.
Either parent can trigger a formula assessment through myIR without the other parent's agreement, and either can apply for the amount to be reviewed if income or care arrangements change significantly during the year — IRD does not wait for the next annual assessment if circumstances shift materially. Parents can also opt for a private agreement instead of the IRD formula, though this requires both parents' consent and generally sits outside IRD's collection and enforcement mechanisms unless registered with them.
Example: working out a parent's child support income
A paying parent earns $70,000 in taxable income for the 2026-27 child support year and supports no other dependent children. Subtracting the standard living allowance of $30,557 gives a child support income of $39,443.
This $39,443 feeds into the combined-income formula alongside the other parent's child support income to determine each parent's share of the children's estimated costs, before the care-share percentage is applied. Even if the resulting formula share came out very low, the statutory minimum annual liability of $1,211 for 2026-27 would still apply as a floor.
Frequently asked questions
Can parents agree on child support privately instead of using IRD's formula assessment?
Yes — parents can enter a private agreement setting their own amount, but both must consent, and unless it's registered with IRD it generally sits outside IRD's automatic collection and enforcement powers.
What happens to a child support assessment if the paying parent's income changes during the year?
Either parent can apply to IRD for a reassessment when income changes materially, rather than waiting for the next annual assessment, so the formula can be updated mid-year to reflect the new income.
Does child support change if the care arrangement for the children changes partway through the year?
Yes — the percentage of nights each parent cares for the children directly affects the formula outcome, so a genuine change in care arrangements is grounds to apply for a reassessment reflecting the new care split.
Related Terms
IRD
Inland Revenue Department (IRD), commonly known as Inland Revenue or simply IRD, is the New Zealand government agency responsible for collecting taxes, distributing social support payments, and enforcing tax compliance.
Working for Families
Working for Families (WFF) is a government scheme that provides tax credits to families with dependent children aged 18 or under (or 16–18 and not receiving a benefit or student allowance).
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