Basic formula

This formula is for parents with only 1 child support assessment.

Read about parents with 2 or more assessments.

Basic 8 step formula

Step What we do This step is about

1
Work out each parent’s child support income

We calculate each parent’s child support income. This is a parent’s adjusted taxable income minus a self-support amount and any relevant dependant allowance. For more information about relevant dependant allowances, see child support assessments and second families.

A parent may be able to estimate their income. Read more about income used in calculating a child support assessment.

Income

2
Work out the parents’ combined income

We add both parents' incomes to work out a combined child support income.

Income

3
Work out each parent’s income percentage

We work out each parent’s income percentage by dividing each parent's income by their combined total.

Income

4
Work out each parent’s percentage of care

We calculate each parent's percentage of care.

Care

5
Work out each parent’s cost percentage

We work out each parent's cost percentage using the care and cost table.

Care

6
Work out each parent’s child support percentage

We subtract the cost percentage from the income percentage for each parent. We call this the child support percentage. The result will determine if a parent pays or receives child support.

If it’s a negative percentage, we assess that parent as the parent to receive child support. This is because their share of costs for the child is more than met by the amount of care they provide.

If it’s a positive percentage, we assess that parent as the parent to pay child support. This is because they’re not meeting their share of the costs for the child directly through care.

If you have different care arrangements for various children, you might have different child support percentages for each child.

We go on to steps 7 and 8 using only the positive child support percentage.

Child support percentage

7
Work out the costs of children

We work out the costs for each child based on the parents' combined total income using the costs of children table.

Costs of children

8
Work out the child support amount

We work out the total amount of child support payable by multiplying the positive child support percentage by the costs of the child. This final figure is the amount the paying parent needs to pay the other parent.

Child support to pay

Care and cost table

Your care percentage is the amount of time you spend with the child. This helps us to work out your cost percentage.

Your cost percentage is your share of the child’s costs that you meet directly through care.

Care percentage Equal to number of nights a year Equal to number of nights a fortnight Care level Cost percentage
0-13% 0-51 1 Less than regular care 0%
14-34% 52-127 2-4 Regular care 24%
35-47% 128-175 5-6 Shared care 25% plus 2% for every percentage point over 35% of care
48-52% 176-189 7 Shared care 50%
53-65% 190-237 8-9 Shared care 51% plus 2% for every percentage point over 53% of care
66-86% 238-313 10-12 Primary care 76%
87-100% 314-365 13-14 More than primary care 100%

Read about how your care percentage affects child support.

Costs of children

The costs of children tables recognise that raising children costs different amounts for different people. Because of this we work out your children’s costs based on the:

About the tables

Steps 1 and 2 of the basic 8 step formula explain what combined child support income is.

Under the formula, we deduct an amount for each parent to support themselves. We calculate the costs of raising children according to the remaining combined child support income of both parents. We divide the costs between the parents according to their share of the combined income.

The costs of children table represents net costs after Family Tax Benefit. All the figures in these tables are for child support periods starting in 2017.

Read about costs of children for past years in the Child Support Guide on the Department of Social Services website.

Children aged 12 and under

Parents combined child support income Cost of 1 child Cost of 2 children Cost of 3 or more children
$0 to $36,231 17c for each $1 24c for each $1 27c for each $1
$36,232 to $72,462 $6,159 plus 15c for each $1 over $36,231 $8,695 plus 23c for each $1 over $36,231 $9,782 plus 26c for each $1 over $36,231
$72,463 to $108,693 $11,594 plus 12c for each $1 over $72,462 $17,028 plus 20c for each $1 over $72,462 $19,202 plus 25c for each $1 over $72,462
$108,694 to $144,924 $15,942 plus 10c for each $1 over $108,693 $24,274 plus 18c for each $1 over $108,693 $28,260 plus 24c for each $1 over $108,693
$144,925 to $181,155 $19,565 plus 7c for each $1 over $144,924 $30,796 plus 10c for each $1 over $144,924 $36,955 plus 18c for each $1 over $144,924

Income over $181,155

Costs don’t go up past this cap

$22,101 $34,419 $43,477

Read more about parents combined child support income.

Children aged 13 or older

Combined child support income for 1 year Cost of 1 child Cost of 2 children Cost of 3 or more children

$0 to $36,231

23c for each $1

29c for each $1

32c for each $1

$36,232 to $72,462

$8,333 plus 22c for each $1 over $36,231

$10,507 plus 28c for each $1 over $36,231

$11,594 plus 31c for each $1 over $36,231

$72,463 to $108,693

$16,304 plus 12c for each $1 over $72,462

$20,652 plus 25c for each $1 over $72,462

$22,826 plus 30c for each $1 over $72,462

$108,694 to $144,924

$20,652 plus 10c for each $1 over $108,693

$29,710 plus 20c for each $1 over $108,693

$33,695 plus 29c for each $1 over $108,693

$144,925 to $181,155

$24,275 plus 9c for each $1 over $144,924

$36,956 plus 13c for each $1 over $144,924

$44,202 plus 20c for each $1 over $144,924

Income over $181,155

Costs don’t go up past this cap

$27,536 

$41,666

$51,448

Read more about parents combined child support income.

Children of mixed ages

Combined Child Support income for 1 year Cost of 2 children Cost of 3 or more children
$0 to $36,231

26.5c for each $1

29.5c for each $1

$36,232 to $72,462

$9,601 plus 25.5c for each $1 over $36,231

$10,688 plus 28.5c for each $1 over $36,231

$72,463 to $108,693

$18,840 plus 22.5c for each $1 over $72,462

$21,014 plus 27.5c for each $1 over $72,462

$108,694 to $144,924

$26,992 plus 19c for each $1 over $108,693

$30,978 plus 26.5c for each $1 over $108,693

$144,925 to $181,155

$33,876 plus 11.5c for each $1 over $144,924

$40,579 plus 19c for each $1 over $144,924

Income over $181,155

Costs don’t go up past this cap

$38,043

$47,463

Read more about parents combined child support income

Page last updated: 4 April 2017

This information was printed Monday 24 April 2017 from humanservices.gov.au/customer/enablers/working-out-child-support-payments-using-basic-formula It may not include all of the relevant information on this topic. Please consider any relevant site notices at humanservices.gov.au/siteinformation when using this material.