Wilmut and Martinson (Child support)
[2025] ARTA 1602
•4 July 2025
Wilmut and Martinson (Child support) [2025] ARTA 1602 (4 July 2025)
Applicant/s: Mr Wilmut
Respondent: Child Support Registrar
Other Parties: Ms Martinson
Tribunal Numbers: 2025/SC029204 and 2025/SC029306
Tribunal: General Member I Sheck
Place:Melbourne
Date:4 July 2025
Decision:
The Tribunal sets aside the decision under review, and, in substitution, decides that:
Mr Wilmut’s care percentage in respect of [Child A] is 58% with effect from 1 August 2024 and 100% with effect from 12 September 2024; and
Ms Martinson’s care percentage in respect of [Child A] is 42% with effect from 23 December 2023 and 0% with effect from 7 August 2024.
CATCHWORDS
CHILD SUPPORT – percentage of care – change to the pattern of care – no pattern of care – determinations revoked and new determinations made – decision under review set aside and substituted
Names used in all published decisions are pseudonyms. Any references appearing in square brackets indicate that information has been omitted from this decision and replaced with generic information pursuant to subsection 16(2AB) of the Child Support (Registration and Collection) Act 1988.
Statement of Reasons
BACKGROUND
Mr Wilmut and Ms Martinson are the parents of [Child A], born on [date]. A case was registered with Services Australia – Child Support (Child Support) for the assessment of child support on 19 February 2019. Child Support has been responsible for collection of the liability since 18 March 2024. The assessment of child support was based on care percentages of 100% to Ms Martinson and 0% to Mr Wilmut.
On 1 August 2024, Mr Wilmut notified Child Support that there was a draft parenting agreement in place between himself and Ms Martinson. In accordance with this agreement [Child A] was in his care from 4 pm each Saturday until school drop-off the following Wednesday. On 28 August 2024, Mr Wilmut provided third-party letters to support the change in care. On 12 September 2024, Mr Wilmut notified Child Support that he had taken care of [Child A] for 100% of the time since 4 August 2024. She had not returned to her mother on 7 August 2024. On 30 September 2024 Mr Wilmut provided a third party letter to support the further change in care.
On a number of occasions, Child Support attempted to contacted Ms Martinson regarding the care changes but were unsuccessful. On 1 October 2024, a Child Support officer determined that there would be no change to the care assessment. A second decision was made by a Child Support officer on 1 October 2024 that Ms Martinson’s care percentage for [Child A] was 43% with effect from 23 December 2023 and Mr Wilmut’s care percentage was 57% with effect from 11 June 2024. The parties were notified of both of these decisions by letter. A further decision was made on 11 October 2024 that Mr Wilmut’s care percentage for [Child A] was 100% with effect from 12 September 2024.
On 29 October 2024, Ms Martinson objected to both care decisions, stating that [Child A] had never left her care. She also provided third-party letters to support that there had been no change in care. On 15 January 2025, an objections officer of Child Support allowed the objection to both decisions and determined that Ms Martinson’s care percentage for [Child A] remained 100%.
By applications both received on 22 January 2025, Mr Wilmut asked this Tribunal to review the decisions of the objections officer. On 30 June 2025, the Tribunal conducted a hearing at which Mr Wilmut gave evidence by MS Teams audio. Ms Martinson had been given notice of the hearing and the scheduled time. The Tribunal telephoned Ms Martinson 3 times at the scheduled time but the phone was not answered. The Tribunal proceeded to determine the matter in Ms Martinson’s absence. The Tribunal had before it the relevant documents from Child Support (pages 1 to 326), which had been copied to the parties.
CONSIDERATION
The legislative provisions relevant to this decision are contained in the Child Support (Assessment) Act 1989 (the Act) and the Child Support (Registration and Collection) Act 1988. The Act sets out the statutory formula for the calculation of child support, which takes into account each parent’s adjusted taxable income and the level of care they provide for each child of the assessment. The provisions require Child Support (and the Tribunal on review) to determine a percentage that corresponds with the actual care of the child that the Registrar is satisfied that the responsible person has had, or is likely to have, during the care period.
Has there been a change in care?
As at August 2024, Child Support had recorded that in respect of [Child A], Ms Martinson had an attributed percentage of care of 100% and Mr Wilmut 0%. The first issue is whether the care that was actually taking place corresponded with the recorded percentages of care.
The background to the case is as set out above. Mr Wilmut told the Tribunal that since around the middle of 2023 he and Ms Martinson had been having roughly 50/50 care of [Child A]. They didn’t notify Child Support. They tried to do their own parenting plan. Mr Wilmut said that he did a lot of research online to work out what should be included. They sat on the phone for about 3 hours working it all out. Mr Wilmut printed out a copy of the agreement so that Ms Martinson could seek legal advice if she wanted to but she refused to sign the agreement and told him to shove it. The Tribunal asked Mr Wilmut whether there were any other agreements, including any orders made by the Court, that related to [Child A’s] care arrangements and he said there were not. They put the agreement together around January 2024. He had already been having [Child A] with him from the Saturday afternoon to Wednesday morning for some time. The agreement wasn’t always followed. Sometimes Ms Martinson would just take [Child A] out of school and he would not have her for that week. The Tribunal asked Mr Wilmut why he did not notify Child Support of the care arrangements until August 2024. He responded that he had moved house and misplaced his paperwork. Also he had trouble logging into his Child Support account and uploading documents.
Mr Wilmut said that from August 2024 he has had [Child A] with him full-time. At the beginning of the 2025 school year he moved her to a different school, closer to where he lives. The Tribunal took Mr Wilmut to a text message,[1] which states in part “Well 193 days left. That’s how many days I wanted to speak to her but you denied me.” Mr Wilmut responded that when [Child A] had been in Ms Martinson’s care (from the Wednesday to the Saturday of each week) he would attempt to call [Child A] at night to talk to her and say good night but Ms Martinson would block his calls. The 193 days he refers to in the text occurred between the start of 2023 and February 2024.
[1] Hearing papers, page 269
The Tribunal asked Mr Wilmut whether there had been any further changes to the care arrangements. Mr Wilmut replied that [Child A] had spent the weekend with Ms Martinson but was now back at school. She was with him all of the time but Ms Martinson would call every now and then to have [Child A] with her for a night or a weekend. The Tribunal asked Mr Wilmut how often this occurred. Mr Wilmut responded that he kept a note in his diary when [Child A] was with Ms Martinson. There was no pattern to it. From August 2024 to the day of the hearing (30 June 2025) [Child A] has stayed with Ms Martinson overnight on 41 occasions.
As noted above, Ms Martinson provided Child Support with very little evidence regarding the care arrangements for [Child A] and she did not attend the hearing and speak to the Tribunal. Mr Wilmut and Ms Martinson have both provided documents from third parties supporting their claims regarding [Child A’s] care. The Tribunal noted in particular a letter from Ms Martinson’s neighbour [Neighbour A] dated 14 October 2024, in which [Neighbour A] states that Ms Martinson has full-time care of [Child A], [Neighbour A] sees [Child A] every day and their children go to school together. A Child Support officer called [Neighbour A] on 19 December 2024 and she said that she hadn’t seen [Child A] “for a little bit” as Mr Wilmut has taken her.
On balance, the Tribunal accepts Mr Wilmut’s evidence regarding the care arrangements, which has been broadly consistent. The Tribunal consequently finds that from 23 December 2023 [Child A] has been in the care of Mr Wilmut from Saturday afternoon to Wednesday morning and in the care of Ms Martinson the remainder of each week. [Child A] was due to return to the care of her mother on Wednesday 7 August 2024 but did not do so. Since 7 August 2024, [Child A] has generally been in the care of Mr Wilmut and has spent time with her mother. She has stayed overnight with Ms Martinson on 41 nights in the period 7 August 2024 to 30 June 2025, which is 12.5% of the time.
Should the existing care determinations in relation to [Child A] be revoked?
The Tribunal has found that from 23 December 2023 the care arrangements for [Child A] did not correspond with the care percentages recorded by Child Support. Whether the existing determinations, that Ms Martinson’s care was 100% and Mr Wilmut’s 0%, can be revoked depends on whether there was a care arrangement in place at the time of the care change and if so, whether the party who had less care than they should have under such an arrangement was taking reasonable steps to ensure that the care arrangement was complied with (per section 51 of the Act). The term care arrangement for child support purposes has the same meaning as for family tax benefit purposes and is defined in the family assistance legislation as follows:
"care arrangement" in relation to a child means:
(a) a written agreement between the parents of the child, or between a parent of the child and another person who cares for the child, that relates to the care of the child; or
(b) a parenting plan for the child; or ...
Mr Wilmut has provided a document entitled “Parenting/ Custody Agreement Draft” that was drawn up in early 2024. The document is not signed by either of the parties and the Tribunal was unable to conclude that Ms Martinson was in agreement with the terms set out in the document. This means that section 51 does not apply.
Subsection 54F(1) of the Act also sets out circumstances in which a determination of a percentage of care must be revoked. Specifically, it states that an existing determination must be revoked if the Registrar is notified that the care taking place does not correspond with the responsible person’s existing care of the child or children and there would be a change to the cost percentages of the parties if the actual care percentages were to be taken into account.
Mr Wilmut notified Child Support on 1 August 2024 that the care taking place did not correspond with the existing care of [Child A] from 23 December 2023. As discussed above, the Tribunal has calculated that Mr Wilmut had 58% of the care of [Child A] with effect from 23 December 2023 (4 nights per week). A care percentage of 58% equates to a cost percentage of 61%. This differs from his recorded care percentage of 0% at that time, which also has a cost percentage of 0%. Accordingly, the previous determinations of care, that Mr Wilmut had a percentage of care of 0% and Ms Martinson had a percentage of care of 100%, must be revoked and new care determinations made.
Date of effect of the decision to revoke the first care determinations
In terms of the date of effect of the new care determinations, if a party has advised of the care change within 28 days of the change, then the new determination takes effect from the date of the change. That is not the case here. The notification by Mr Wilmut of the change in care was received by Child Support some 8 months after the change of care event that happened on 23 December 2023.
As the notification of the care change was more than 28 days after the stated change of care event, subsection 54F(3) provides:
(3) The revocation of the determination takes effect at the end of:
(a) if the Registrar or Secretary is notified, or otherwise becomes aware, of the matter referred to in paragraph (1)(a) within 28 days after the change of care day for the responsible person - the day before the change of care day; or
(b) if the Registrar or Secretary is notified, or otherwise becomes aware, of that matter more than 28 days after the change of care day for the responsible person and:
(i) the responsible person's care of the child has increased - the day before the Registrar or Secretary is notified, or otherwise becomes aware, of that matter; or
(ii) the responsible person's care of the child has reduced - the day before the change of care day.
The term “responsible person” is defined at section 5 of the Act as a parent or non‑parent carer of the child; in this case, the parents, Ms Martinson and Mr Wilmut. As Mr Wilmut’s care of [Child A] had increased from 0% to 58%, the determination as to his percentage of care must be revoked from 31 July 2024, which is the day before notification of the care change. As Ms Martinson’s care had reduced, the revocation of her care determination must take effect from the day before the change day, that is, 22 December 2023.
New care determinations are then made from the day after the relevant revocations, setting out the new care percentages for each of the parties.
Date of effect of the decision to revoke the second care determinations
There was then a second change to the care arrangements. From 7 August 2024, [Child A] did not return to her mother’s regular (3 nights per week) care as was previously in place. Although Mr Wilmut agrees that [Child A] has spent some time with her mother since 7 August 2024 this does not disturb the overall pattern of care established by Mr Wilmut, which is that [Child A] is in his care for 100% of the time (and the Tribunal notes that in any event, a care percentage of less than 14% would give a cost percentage of 0% for Ms Martinson). Although Mr Wilmut had a number of contacts with Child Support during August 2024 he did not notify of the second change to the care arrangements until 12 September 2024.
Again, the date of notification was more than 28 days after the event therefore section 54F(3) must apply. As Mr Wilmut’s care of [Child A] had increased again from 58% to 100%, the determination as to his percentage of care must be revoked from 11 September 2024, the day before notification of the care change. As Ms Martinson’s care had reduced from 42% to 0%, the revocation of her care determination must take effect from the day before the change day, that is, 6 August 2024. New care determinations are then made from the day after the relevant revocations.
DECISION
The Tribunal sets aside the decision under review, and, in substitution, decides that:
Mr Wilmut’s care percentage in respect of [Child A] is 58% with effect from 1 August 2024 and 100% with effect from 12 September 2024; and
Ms Martinson’s care percentage in respect of [Child A] is 42% with effect from 23 December 2023 and 0% with effect from 7 August 2024.
Date of hearing: Monday, 30 June 2025
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