NZ Child Support Calculator
Estimate child support payments for the 2025-26 or 2024-25 tax year using the IRD administrative assessment formula. See income shares, cost of children, care adjustments, and a step-by-step breakdown.
Quick Answer
Child support in NZ is calculated using income shares. Each parent's adjusted income is compared, and the higher earner typically pays a portion of the cost of raising the children, offset by the amount of care they provide.
Key Facts — 2025-26
Formula
Income Shares
Living Allowance (no deps)
$23,000
Shared Care Threshold
28% of nights
Age Groups
0-12 and 13+
Taxable?
No
Minimum Payment
~$18/week
Parent 1: 0 nights (0.0%)
How NZ Child Support Is Calculated
New Zealand uses an income shares model to calculate child support. IRD (Inland Revenue) administers the formula, which considers both parents' incomes, the number and ages of children, and how much time each parent spends caring for them.
Step 1: Each parent's taxable income is reduced by a living allowance. This allowance varies based on the number of other dependent children the parent supports.
Step 2: The adjusted incomes are combined to form the child support income. Each parent's share is their proportion of this combined total.
Step 3: The cost of children is determined from IRD tables based on the combined income and the number/ages of children. Older children (13+) cost more than younger ones.
Step 4: A care cost offset is applied based on the number of nights each parent has the children. More nights of care = higher offset = less child support payable.
Step 5: Each parent's liability is calculated as (income share × cost of children) minus (care offset × cost of children). The parent with the positive net liability pays the other parent.
Shared Care Cost Offsets
| % of Nights | Approximate Nights | Cost Offset |
|---|---|---|
| Less than 28% | < 102 nights | 0% |
| 28% – 34% | 102 – 124 nights | 24% |
| 35% – 47% | 128 – 172 nights | 25% – 49% |
| 48% – 52% | 175 – 190 nights | 50% |
| 53% – 65% | 193 – 237 nights | 52% – 76% |
| 66% – 72% | 241 – 263 nights | 76% |
| More than 72% | > 263 nights | 100% |
Frequently asked questions
How is child support calculated in New Zealand?
IRD uses an administrative assessment formula. Each parent's taxable income is reduced by a living allowance, then income shares are calculated. The cost of children is looked up from IRD tables based on combined income and the number/ages of children. Care time offsets are applied based on nights of care. The parent with the higher income share and lower care time typically pays the difference.
What is the living allowance for child support?
The living allowance is deducted from each parent's income before calculating child support. For 2025-26, it is approximately $23,000 with no other dependents, $30,000 with 1 dependent, $34,000 with 2 dependents, and $38,000 with 3 or more dependents.
How does shared care affect child support?
Shared care reduces the amount payable. If you have the children less than 28% of nights (about 102 nights), there is no care cost offset. At 28-34% you receive a 24% offset. From 35-47% it increases gradually. At 48-52% (substantially shared care) each parent gets a 50% cost offset. Over 72% care means a 100% offset — the other parent pays you.
What is the minimum child support payment in NZ?
IRD sets a minimum annual child support amount. Even if the formula produces a very low figure, the paying parent is still required to pay a minimum rate — approximately $18 per week ($936 per year) as of 2025-26.
Does child support change when children turn 13?
Yes. The IRD cost of children tables have different rates for children aged 0-12 and children aged 13+. Older children are considered more expensive to support, so child support may increase when a child turns 13.
Can I change my child support assessment?
Yes. You can apply to IRD for an administrative review if your circumstances have changed significantly — for example, income changes, changes in care arrangements, or special expenses. Both parents can request a review.
Is child support taxable income?
No. Child support payments received are not taxable income for the receiving parent. Likewise, child support payments made are not tax-deductible for the paying parent.
What if one parent earns nothing?
If one parent has zero income, their adjusted income is zero and their income share is 0%. The entire income share belongs to the other parent. However, the parent with zero income may still be assessed at a minimum amount if they are the liable parent.
Sources
Related Calculators
Last updated April 2026. Reflects 2025-26 tax year rates.