When you apply for a child support formula assessment, we consider your income and family situation, the child's age, and who they live with.
Overview
We use the child support formula to work out how much child support should be paid, and we manage collection and payment of that child support.
It’s a good option if you cannot agree on an amount with the other parent or are not on good terms with them. If you want to easily change the amount as your circumstances change, it may be better to choose a private or voluntary agreement instead.
If you get an Unsupported Child’s Benefit, you must apply for a formula assessment for that child.
If the child lives with both parents some of the time, we may not know who pays who until after you have applied.
The formula
The child support formula is based on:
- both parents’ incomes and living situations (non-parent carers are not included)
- the amount of time the child lives with each parent
- the cost of bringing up a child of different ages
- the cost of any other dependent children each parent may have.
Here's a detailed explanation of how child support formula assessments are calculated. If you want to work out your own child support, use our handy calculator instead.
Child support payments calculator
1. Your income
We start with your taxable income from the last year, or 2 years ago if you file an IR3 individual income tax return.
2. Allowances
Then we take away allowances. These include:
- a living allowance, which is updated each year - everyone gets one of these
- dependent child allowances - for any child living with you, that you are the legal parent of, and who is not having child support paid or received for them
- multi-group allowances - if you are paying or receiving child support for more than one other parent or family.
3. Total child support income
Next, we combine your income with the other parent's to get the total income available to support your children.
4. Income percentage
Then we look at what percentage each parent has of the total child support income. For example, one parent may have 30%, and the other 70%. This is the money they have available for the children.
5. Care cost percentage
We look at who the child lives with – the more time a child is in your care, the more you pay for their ongoing costs. If a child lives with only one parent, they have 100% of the ongoing costs. If a child lives with each parent 50% of the time, the parents each have 50% of the ongoing costs.
6. Working out who should pay
Finally, we use the income percentage and care cost percentage to work out who should pay who, and how much.
If the child lives with one parent full-time, that parent will receive child support.
If the child lives with each parent some of the time, payments will depend on their incomes and how much time the child lives with each.
In this situation, it’s possible that the parent with more care could end up paying the other, if they also have a much higher income.
It’s also possible that no one will have to pay. This happens when all the following apply.
- The child lives with each parent some of the time (there is recognised care).
- One parent has much less income than the other.
- The parent with less income also has less than 35% care, so cannot receive payments.
Sharing care of a child
If a child lives with each parent or carer some of the time in an ongoing arrangement, we need to confirm what percentage of the time they live with each one.
How to set up a formula assessment
Check that you, the child and the parent or parents qualify for this type of child support. If you all meet the requirements, you can apply online, over the phone or on paper.
Everyone needs IRD numbers
If you or your children do not have IRD numbers yet, here’s how to apply.
IRD number applications – Living in New Zealand and not a new arrival
Proof of parentage
When you apply, you’ll need to provide proof of who the child’s parents are – for example, a full birth certificate. If you do not have a document to prove you’re the parent, you can acknowledge this in writing instead.
Paternity orders
If you need help proving that someone is a parent, you can apply to the Family Court for a paternity order. We can then backdate your child support to the date we received your application, as long as:
- you apply to the Family Court for the paternity order within 60 days of applying for your child support
- you give us a copy of the paternity order within 60 days of it being made by the Family Court.
Otherwise, we’ll start your child support from the date you give us the paternity order.
Safety concerns
Tell us if you believe that using your real name in your application will cause safety concerns for you, a carer or your child. We may be able to leave your name out when we communicate with the other parent.
Apply for child support – formula assessment
How payments work
Once we accept an application, we send out notices to each parent or carer showing who should pay and how much.
Payments are due to us by the 20th of the following month, then to the receiving carer by the 23rd of the same month.
Payment cycles and due dates
Making payments - paying parents
Ending formula assessments
Formula assessments end when:
- you, the other parent or the child no longer qualify for child support
- the receiving carer cancels child support – including if they want to begin a private agreement
- the parents agree to register a voluntary agreement instead.
If you get an Unsupported Child’s Benefit for a child, you cannot cancel a formula assessment or change to a different type of agreement as long as that child still qualifies and lives with you.
Check the requirements for getting or cancelling child support.
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