Child support assessment

How your income affects your child support

We consider each parent’s income equally when we make a child support assessment. We don’t use income from non parent carers.

What income information we use

We can usually use information about your income from the Australian Taxation Office (ATO).

The income we base your payments on is your adjusted taxable income for the last relevant year. This means the financial year that ended before your current child support period.

If you live overseas, financial year means the financial year of the country you live in. Read about child support when parents and children live overseas.

To make sure we base your child support on the right income, always lodge your tax return on time.

If you haven’t lodged your tax return for the last relevant year

We’ll work out a provisional income for you. This is what we think your adjusted taxable income is likely to have been.

You need to give us your income details for that year as soon as you can. You shouldn’t wait until you lodge your tax return.

We may make a new assessment when you or the other parent lodge a tax return for the year.

If you live overseas, we won’t know when you lodge a tax return in the country where you live. If you have a child support assessment from us, you need to tell us your last financial year’s income. You must do this at the start of each child support period. You may need to give us proof of your income.

Read about child support when parents and children live overseas.

If you need to tell us your income

If you haven’t lodged a tax return, tell us your income as soon as you can by either:

If you have income from Norfolk Island

If you earned income on Norfolk Island in 2015-16, you should tell us. To do this, complete the Income declaration - Norfolk Island income for the 2015-16 financial year form.

If you think we’ve got the other parent’s income wrong

Call us on the child support general enquiry line if you don’t think we’re using the right income.

We’ll look into it and update the assessment if necessary.

Changes to your income 

If your income changes, call us on the child support general enquiry line to discuss what you can do.

You should tell us about any changes to your income when they happen. We may be able to change your child support assessment. In general, we can’t backdate the change, so tell us as soon as you can.

How income affects your assessment

We add both parents’ incomes together. Then we work out each parent’s share of the total income. This tells us their share of the children’s costs.

You may be meeting some or all of these costs by caring for the child.

Read how your percentage of care affects your payments.

Read about the assessment formula.

How to estimate your income

Your income may have changed since your last assessment. If so, we may be able to use an estimate of your income for this financial year instead.

You can give us an income estimate if:

  • the ATO has assessed your income for the financial year used in your assessment
  • you haven’t lodged your tax return for the financial year used in your assessment, but you've declared your income 
  • your current adjusted taxable income is at least 15% lower than that amount.

You may not be able to submit an estimate if your child support involves:

If you want to submit an estimate

You can submit an estimate:

Or you can complete the Estimate of income for use in Child Support Assessment form and submit it either:

Make your estimate as exact as you can.

If you get it wrong you may end up with a debt.

If you need to update your estimate

Your income changes

If you’ve made an estimate, you must make a new one if your income goes up or down.

Do this as soon as you can. If your income goes down, we can’t backdate it.

Your estimate ends before your child support period

Your income estimate lasts until the end of the financial year. Your child support period may continue into the new financial year.

If this happens you should give us a new income estimate. Do this before the end of the current financial year.

If you don’t submit a new estimate we’ll base your assessment on the income from the last financial year.

If you don't update your estimate

After the financial year ends we compare your estimate to your actual income for the year.

If the estimate is lower you may have to:

  • pay off a debt
  • pay back an overpayment.

How provisional income works

If the ATO hasn’t told us your income for the financial year, we base your payments on provisional income.

If we work out your provisional income

You can tell us your adjusted taxable income for the most recent financial year. We’ll use this if we think it’s likely to be right.

We may ask you for a copy of some recent pay slips to help us.

If we don’t have enough information about last year we’ll use your tax return for the year before that. We’ll adjust it for inflation.

If you don’t have a tax return for that year we’ll use your most recent tax return and:

If you don’t have a tax return for any year we’ll use two-thirds of the male total average weekly earnings.

If you lodge your tax return late

We work out your provisional income when you haven’t lodged a tax return on time. If your actual income was lower than your provisional income, we can’t usually go back and change your child support.

Change of assessment

If you have special circumstances you may be able to apply for a change of assessment. You can do this for the time when we were basing your payments on the higher income.

Call the Child Support general enquiry line so we can let you know how to apply and the process. There are time limits for applying, so contact us as soon as you can.

What if you earn extra income after you separate

If you earn extra income after you separate you should call us on the Child Support general enquiries line. You may be able to exclude it from your child support assessment.

You can only exclude income for 3 years after separating.

You may be able to exclude up to 30% of your adjusted taxable income.

Both parents can apply to do this.

If you want to apply to exclude income

To apply to exclude income, fill in the Application for Post Separation Income to be Excluded form.

You need to show you earned the extra income in a pattern that started after separating. This could be from:

  • getting a new job on a higher salary
  • opening your business for longer hours
  • getting a second job.

You also need to show you wouldn’t have earned it in the normal course of events. For example it can’t be from:

  • a regular pay increase
  • your usual pattern of overtime.

Page last updated: 4 December 2018