NZ IRD Child Support Formula Assessment (Income & Care Shares) Calculator
Calculate Inland Revenue (IRD) child support under the 8-step formula: compare parental income shares against care nights percentages and child expenditure tables.
Calculate Inland Revenue (IRD) child support under the 8-step formula: compare parental income shares against care nights percentages and child expenditure tables.
Calculate Inland Revenue (IRD) child support under the 8-step formula: compare parental income shares against care nights percentages and child expenditure tables. Calculate exact, penny-accurate projections compliant with 2026 Inland Revenue (IRD) • ACC • Reserve Bank of New Zealand (RBNZ) standards using Calconova's deterministic IEEE-754 (Decimal.js) calculation engine with instant breakdowns.
$132.48 /week equivalent
Paying Parent
73 nights/yr provided
1 children combined cost
Gross taxable income for each parent and annual nights of care.
Income shares, care percentages, and assessment.
\text{CS Income} = \max(0, \; \text{Taxable Income} - \text{Living Allowance } (\$29,863)) \\
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\text{Income \%} = \frac{\text{Parent CS Income}}{\text{Combined CS Income}} \\
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\text{Child Support \%} = \text{Income \%} - \text{Care Cost \%} \\
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\text{Annual Assessment} = \text{Child Support \%} \times \text{Expenditure on Children}Under the NZ Child Support Act 1991, Inland Revenue uses an 8-step income-shares formula. Each parent's taxable income minus the statutory living allowance ($29,863 for 2024/2025) yields their Child Support Income. The parent's income percentage minus their care cost percentage determines their Child Support Percentage, which is applied to the official Expenditure on Children table.
All calculations, amortizations, and scenario projections displayed on this page are strictly for informational and educational purposes. Nothing herein constitutes investment, financial, tax, or legal advice. Actual Reserve Bank of New Zealand (RBNZ) interest rates, IRD PAYE brackets, ACC Earner's Levy, KiwiSaver regulations, and lender criteria may vary. Calconova explicitly disclaims all liability for any decisions taken based upon these calculations. Consult a qualified financial advisor, CPA, or official Inland Revenue documentation prior to executing financial commitments.
Care is measured by nights per year. Providing care for at least 52 nights (14%) qualifies you for a 24% care cost credit. Between 173 and 192 nights (48%-52%), care is deemed 50/50 shared, and child support only equalizes any disparity in income shares.
For the 2024/2025 year, the statutory minimum child support liability for a paying parent is $1,154 per year (approx $96.16 per month or $22.20 per week).
Parents can make a voluntary private agreement or register for a statutory formula assessment with Inland Revenue. When registered with IRD, payments can be automatically deducted from the paying parent's wages.
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