Child Support - how it works 


What is Child Support?
How are child support payments calculated?
If I share care of my child do I still have to pay child support?
My income fluctuates a lot because I do seasonal work, how do I know how much I need to pay?
We’ve got a voluntary agreement about how much to pay. Do we have to tell the IRD?
I’m in prison. Do I still have to pay child support?

What is Child Support?

The child support system collects money from parents not living with their children to help financially support those children. The money is paid to the 'custodian' (meaning caregiver) of a child under 19 by the parent who is not living with the child. This usually happens when couples separate or get divorced. Custodians can also be people such as grandparents or organisations such as Child, Youth and Family. 

Inland Revenue (IRD) calculates monthly child support payments based on income, living costs, and number of dependent children and handles all child support arrangements. IRD collects the money from the parent who has to pay child support (the ‘paying parent’), and passes it on to the custodial parent.

If the custodial parent is receiving a Work and Income benefit then they have to apply for child support; otherwise they can decide whether to apply or not.

Important changes to child support take effect from April 2015. You can read about them on the IRD website.   

If you need to apply for child support, you can call the IRD on 0800 227 771 or see the IRD webpage on Applying for Child Support. If you don't want to apply for Child Support, but you'd like more general information, see the IRD Child Support website.


How are child support payments calculated?

Inland Revenue uses a standard child support formula to calculate how much child support the paying parent must pay (also known as the 'formula assessment'). This is done in four steps:

  1. Work out the paying parent's taxable income for the child support year. 
  2. Subtract a living allowance amount (this varies depending on how many children live with the paying parent and whether a spouse or partner is living with them).
  3. Multiply the result by a percentage rate (this varies depending on how many children the paying parent will pay child support for and whether there is a shared care arrangement in place for those children).
  4. The result is divided into twelve monthly amounts which have to be paid each month.


If I share care of my child do I still have to pay child support?

Shared care
If you care for your child more or less equally with the child’s main carer (this usually means that your care for the child at least 40% of the (146 nights) child support year - from 1 April to 31 March), you can apply to Inland Revenue to recognise the care arranged as being “shared care”.

In a shared care arrangement, you will probably still have to pay child support. However you may be entitled to a reduction in the amount you have to pay depending on the number of children involved and whether you have a partner or other children living with you. 

More information about how shared care affects child support is in the IRD booklet Understanding Shared Care (IR156).

When care arrangements are not considered shared care
If you care for the child some of the time but don’t fall under the definition of providing “shared care” then your child support payments will be the same as if you don’t provide any care.

If you aren’t sure whether the child’s care arrangement meets the shared care criteria, you can fill out an IR120 Child Support Shared Care Questionnaire (choose the one for the appropriate child support year) and send it to IRD. They will use the information provided to work it out for you.

Note that changes to child support and shared care take effect from April 2015. You can read about them on the IRD website


My income fluctuates a lot because I do seasonal work, how do I know how much I need to pay?

The IRD uses your taxable income when calculating how much child support you should pay (see How are child support payments calculated?), and it is usually your income from either the previous year or two years.

If you are earning at least 15% less now than you were in previous years, you can choose to estimate your income (there are circumstances when you don’t have this choice). To do this, complete an IR104 Estimate of income for child support assessment form and send it to Inland Revenue (you can also do it online).

Inland Revenue will then send you a notice of assessment advising you of what your payments will be according to your income assessment.

At the end of the child support year, Inland Revenue will work out from your tax return or personal tax summary, whether you have overpaid or underpaid child support. If you have overpaid, you’ll have reduced child support obligations for the following year. If you have underpaid, you’ll be notified and given 30 days to pay the difference. This is called the end-of-year square-up.


We’ve got a voluntary agreement about how much to pay. Do we have to tell the IRD?

A voluntary child support agreement is when the parents come to their own agreement about the payment of child support instead of using formula assessed child support.

Unless the custodial parent is receiving a benefit, you do not have to register a voluntary child support agreement with Inland Revenue. If you do register the agreement with the IRD, they will administer the payments (and enforce them if necessary).

Registering a voluntary agreement with IRD
This option is only allowed if the paying parent, custodial parent and their child or children either are New Zealand citizens or ordinarily live in New Zealand.

To register your voluntary agreement with Inland Revenue you need to send it to them along with completed IR102 Registration of voluntary agreement or court order for child support. A voluntary child support agreement will only be accepted if your agreement is: 

  • in writing, 
    • made between the paying parent and the custodial parent
    • signed by both the paying parent and the custodial parent, 
  • for a “qualifying child” - that is: 
    • aged under 19 years, 
    • not married or in a civil union or de facto relationship, 
    • a New Zealand citizen or ordinarily living in New Zealand
    • financially dependent – not working fulltime nor receiving a benefit or student allowance)
  • for regular payments of the equivalent of at least $10 per week (they can be weekly, fortnightly or monthly).

If the custodial parent is receiving a Work and Income benefit, the payments must be at least that amount which would be calculated using the IRD formula assessment, and the paying parent would only receive the portion of child support money which is over the formula assessment amount (the benefit makes up the rest).

Inland Revenue will advise you of what the monthly payment amount will be, and when they will start. Your agreement will replace the formula assessment once Inland Revenue has accepted your agreement, and the paying parent will make payments to the IRD.

You can call Inland Revenue on 0800 221 221, or read their information about voluntary agreements for child support, if you need more information.


I’m in prison. Do I still have to pay child support?

If you are in prison for at least 13 consecutive weeks, you can apply to stop your child support payments if: 

  • you receive no income while in prison, or 
  • your only income is from investments and averages less than the maximum amount per week (as specified are on the IRD web page about Prison inmates).

To do this, complete a IR105 Prisoner and hospital patient exemption application form and send it to Inland Revenue.

If you don’t meet the above criteria, and your income will be at least 15% less than the income which IRD used to work out your child support payments, you can apply to have the payments recalculated using an estimate of your current income. See the question My income fluctuates a lot because I do seasonal work, how do I know how much I need to pay? for more about estimating your income.

Other exemptions from paying child support
If you are a paying parent you may be able to stop or reduce your payments if:

  • you are in a hospital or drug rehabilitation centre for at least 13 weeks and meet the low or no income criteria (see the IRD’s Hospital patients page for more details) or
  • you are aged under 16 years and you meet the low or no income criteria (more details are on the IRD’s Under 16 page or
  • you are a victim of a sexual offence, a result of which is the birth of the child (for more details see the IRD’s Victims of sexual offences page).