The Guides to Social Policy Law is a collection of publications designed to assist decision makers administering social policy law. The information contained in this publication is intended only as a guide to relevant legislation/policy. The information is accurate as at the date listed at the bottom of the page, but may be subject to change. To discuss individual circumstances please contact Services Australia.

2.4.1 When do child support periods start?

Context

A new CSP (1.1.C.150) starts when the Registrar makes a new child support assessment (1.1.C.70). The Registrar makes assessments using the last relevant year of income (1.1.L.10) for the CSP to which the assessment will apply (section 43).

Amending an assessment (that is, adding a new child, or updating an income) does not start a new CSP.

Act reference

CSA Act section 7A, section 31, section 34A, section 34B, section 34C, section 40B, section 93, section 5, section 43

On this page

When the Registrar is required to make a new child support assessment

The Registrar must make new assessments, which apply to new CSPs, in the following circumstances.

Accepting an application for assessment

The Registrar must make an assessment as quickly as practicable after accepting a new application for an administrative assessment (1.1.A.30) of child support (1.1.C.60) (section 31(1)). The CSP for this assessment starts on the day the application was received (section 7A(2)(a)).

Note: A new CSP will not be initiated by:

  • the acceptance of an application from a non-parent carer to receive child support under an existing child support assessment (meaning, there is already an assessment between the parents (1.1.P.10) for the child and no terminating event has occurred) (section 40B(3)), and
  • the acceptance of an application to add a new child to an existing case.

Instead, the Registrar will amend the existing assessment to take account of these events.

Act reference: CSA Act section 7A Meaning of child support period, section 31 Requirement to assess child support on acceptance of application

Accepting a child support agreement that starts a new case

The Registrar must make an assessment as quickly as practicable after accepting a child support agreement that starts a new case (section 93(2)). An assessment and CSP will start on the day the liability to pay child support starts, that is from the day the application for acceptance of the agreement was made to the Registrar (section 7A(2)(b) and section 93(1)(g)).

Act reference: CSA Act section 7A Meaning of child support period, section 93 Liability to pay child support arises on acceptance of application where child support not already payable etc.

Accepting a child support agreement on an existing case where the agreement affects the rate of child support payable

The Registrar must make a new assessment immediately after accepting a child support agreement in an existing case if the agreement affects the rate of child support payable (section 34B(1)). The new assessment applies to a new CSP that starts on the day the agreement alters the rate of child support payable (section 7A(2)(c)). For more details of the date of effect of a child support agreement where child support is already payable, see 6.3.

Act reference: CSA Act section 7A Meaning of child support period, section 34B Administrative assessment for child support period started by new agreement when support already payable

The Registrar makes an assessment when the ATO issues an income tax assessment for one of the parents

The Registrar must make a new assessment when an income tax assessment issues for either parent for the latest financial year that ended during the existing CSP (section 34A). The Registrar must do this as soon as it is practicable after the ATO issues the assessment (section 34A(2)).

If the Registrar makes the new assessment on or before the 15th day of the calendar month, the assessment and new CSP will begin on the first day of the next calendar month.

Example: The Registrar receives a tax assessment of Peter’s income in early October 2026 and makes a new child support assessment on or before the 15th of October 2026. The assessment and CSP will begin on 1 November 2026.

If the Registrar makes the new assessment after the 15th day of the calendar month, the assessment and new CSP will begin on the first day of the calendar month following the next calendar month.

Example: The Registrar receives a tax assessment of Larry’s income after the 15th of October 2026 and makes a new child support assessment before the end of October 2026. The assessment and CSP will begin on 1 December 2026.

Act reference: CSA Act section 7A Meaning of child support period, section 34A Registrar must make assessment when new tax figure is available

When the Registrar is not required to make a new child support assessment

The Registrar may not be required to make a new child support assessment and start a new CSP when the ATO issues an income tax assessment (for the latest year of income that ended during the existing CSP) in 4 circumstances.

Income tax assessment could not affect the rate of child support

A new child support assessment is not required where the tax assessment could not affect the rate of child support payable, for example because the parent's income continues to be below the self-support amount (1.1.S.20) (section 34A(3)(a)).

Example: Casey has a care percentage (1.1.C.20) of 100% for 2 children. The assessment is based on the last relevant income for Casey of $18,140 and for the other parent, George, of $36,314. On 14 July 2021, Casey's 2020-21 tax return issues and the ATI (1.1.A.20) is $17,135.

As Casey's income continues to be below the self-support amount and will not affect the rate of child support payable, the Registrar is not required to make a new assessment and start a new CSP.

Casey's 2020-21 income will be used in the new CSP which will commence after the end of the 15-month period or after George lodges a tax return with an ATI that affects the rate of child support payable (whichever is earlier).

Example: Sarah has a care percentage of 100% for 2 children. The assessment is based on the last relevant income for Sarah of $37,400 and the other parent, Chris, of $36,314. On 10 July 2021, Sarah's 2020-21 tax return issues and the ATI is $17,135.

As Sarah's income is lower than the income that is currently used in the assessment, and this will affect the rate of child support payable, the Registrar is required to make a new assessment and start a new CSP from 1 August 2021.

A new CSP has already started during the current financial year

A new child support assessment is not required where a new CSP has already started during the income year. For example, a new CSP has started because the Registrar has accepted a new agreement, or the other parent's income tax assessment for that year has already started a new CSP.

Example: Peta and Steven's child support assessment commenced on 1 April 2021 with an annual rate of $2,146 based on the 2019-20 taxable incomes (1.1.T.20).

Peta lodges her tax return and, on 28 September 2021, her 2020-21 tax assessment becomes available. A new CSP starts on 1 November 2021 using Peta's 2020-21 ATI of $47,236 and a provisional ATI of $32,231, determined by the Registrar, for Steven.

Steven's 2020-21 tax return issues on 3 December 2021 and his ATI is $34,635. As a new CSP has already started during the income year (to use Peta's ATI of $47,236), the Registrar will not be required to make a new assessment and start a new CSP because of Steven's tax return issuing.

When the assessment was made, an income determined by the Registrar will have been used for the parent (or parents) whose income tax assessment had not yet issued. When the parent's income tax assessment subsequently issues for the same year, it does not trigger a new CSP. The income tax assessment is not for a financial year that ended during the current CSP. The Registrar will amend the existing assessment by replacing the Registrar determined income. The assessment continues and applies to the same CSP.

Similarly, if an amended tax assessment issues for either parent, it will not start a new CSP, but the Registrar may amend the existing assessment to take into account the amended tax assessment.

Assessment based on a change of assessment decision, court order or agreement

A new child support assessment is not required where a change of assessment decision, court order or child support agreement is in place that does not use the parent's taxable income to work out the rate of child support (section 34A(3)(b)).

If the child support agreement, change of assessment decision or court order ceases at any time during the existing CSP, the Registrar is required to make a new assessment when the income tax assessment will affect the rate of child support. The Registrar makes a new assessment during the last calendar month in which the child support agreement, change of assessment decision, or court order has effect. This new assessment applies to a period that starts on the first day of the month following the making of the assessment (section 34A(2)).

Most child support agreements, court orders and change of assessment decisions will end on the last day of a month. If not, the assessment will revert to the formula using the last relevant year of income for the current CSP until the last day of the month. The new assessment using the later year of income will apply to a period that commences on the first day of the month after which the Registrar makes that assessment (section 34A(2)).

Current CSP ending in the same month

A new child support assessment is not required where the existing CSP will finish before the end of the month in which the income tax assessment issues. In these cases, a new CSP starts on the day after the end of the current CSP, rather than the first day of the following month (section 34A(3)(c)).

Can a CSP start retrospectively when a new tax figure is available?

If the Registrar missed making a new assessment when a parent's income tax assessment issued, a retrospective assessment cannot be made (section 34A(2)). The Registrar will make a new assessment at the earliest appropriate time, noting the general rule for practicability outlined above. If a new financial year has started before the Registrar discovers the error, and the last relevant year of income has therefore changed, the Registrar will not be able to make a new assessment based on that income tax assessment. However, the Registrar can amend the existing child support assessment using financial information from the income tax assessment if the information is more accurate for the purposes of the assessment.

Income tax assessment issues in June for the previous financial year

When the ATO issues an income tax assessment that requires the Registrar to make a new assessment, a new CSP starts. The new income tax assessment will relate to the parent's taxable income for the last relevant year of income in relation to the new CSP. The exception is where the Registrar makes a new child support assessment in June to apply to a CSP that starts on 1 July (for example, when the ATO issue an income tax assessment for 2020-21 in June 2022). The last relevant year of income for the new CSP will be the financial year after the year of the income tax assessment that is, 2021-22.

For these cases, the Registrar will make a new child support assessment based upon a provisional income (1.1.P.130) amount for the last relevant year of income for both parents (3.3). When the ATO issues each parent's income tax assessment for the last relevant year of income, the Registrar will amend the child support assessment from the start of the CSP (replacing the provisional income with the actual income in accordance with the date of effect rules outlined in 3.3.3).

Example: A CSP commenced on 1 June 2022 involving parents Elisabeth and Maddi. The last relevant year of income for the CSP is 2020-21. On 3 June 2023, Maddi lodges their tax return for the 2021-22 income year. Elisabeth has not yet lodged their tax return for the 2021-22 income year. A new CSP will commence from 1 July 2024. The last relevant year of income for the CSP commencing on 1 July 2024 is 2022-23, not 2021-22. A provisional income for 2022-23 will be used in the child support assessment for both Elisabeth and Maddi until their respective ATO assessments are available.

After the end of a CSP

The Registrar must make an assessment before the start of a new CSP if an assessment has not already been made for one of the reasons listed above. If the Registrar has not made a new assessment before the start of a new CSP this must be done as soon as practicable after it starts (section 34C). The CSP for this kind of assessment will start on the first day after the day the earlier CSP ended (section 7A(2)(d)).

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