How the care percentage works
Care is counted in nights per year, converted to a care percentage, and then converted again into a cost percentage — the share of the children's costs you're treated as meeting directly. That second conversion is where most people get surprised.
Nights become a care percentage
Services Australia works out care over a 12-month period, usually from your care arrangement or actual pattern of care. One night a fortnight is 26 nights a year, or about 7%. Every second weekend (2 nights) is 52 nights, or 14%. Week about is 182–183 nights, or 50%.
The 52-night threshold
Care below 52 nights a year — under 14% — doesn't change child support at all. A parent with 30 or 40 nights a year is assessed the same as a parent with none. At 52 nights, care becomes "regular care" and starts to count. This threshold is a cliff, not a slope, which is why one extra fortnightly night can matter so much in a care arrangement.
Care converts to a cost percentage
The formula doesn't credit care one-for-one. Instead, each care band maps to a cost percentage:
| Nights per year | Care % | Cost % |
|---|---|---|
| 0–51 | 0–13% | 0% |
| 52–127 | 14–34% | 24% |
| 128–175 | 35–47% | 25% + 2% per point over 35% |
| 176–189 | 48–52% | 50% |
| 190–237 | 53–65% | 51% + 2% per point over 53% |
| 238–313 | 66–86% | 76% |
| 314–365 | 87–100% | 100% |
Notice the jumps. Regular care (any amount from 52 to 127 nights) is worth a flat 24% of costs. The steepest gains happen through the shared care band between 35% and 48% care, where each extra percentage point of care earns two points of cost credit.
Why it matters
A parent pays child support when their share of combined income is larger than their cost percentage. So the care bands directly set how much of your income share is offset by the care you provide. Two families with identical incomes can have very different assessments purely because one care arrangement sits just over a band boundary and the other sits just under it.
Estimate your child support →This is general information about the published formula, not legal advice. Your assessment depends on your circumstances — for a formal figure, contact Services Australia.