Child support assessment

The assessment period

A child support period is the amount of time an assessment covers. It can be up to 15 months.

When a new child support period starts

A child support period will start:

  • on the day you make an application for child support
  • on the day you make an application to accept a child support agreement, if it starts a new case
  • on the day a child support agreement changes a child support assessment,
  • the day after the current child period ends, or
  • when the ATO tells us new income information for the most recent financial year, if that year of income isn’t already used in an assessment

If a new ATO income starts a child support period, it starts:

  • on the 1st day of the next month if we receive the ATO income by the 15th of the month, or
  • on the 1st day of the month after next if we receive the ATO income after the 15th of the month

What happens if there are changes during a child support period

We might need to update your assessment. You must tell us as soon as you can if your circumstances change. For example, we need to know if:

  • your income changes, or
  • the amount of time the child lives with you changes
This information was printed Monday 27 May 2019 from It may not include all of the relevant information on this topic. Please consider any relevant site notices at when using this material.

Page last updated: 11 April 2019