Child Support Private Agreement in Australia: Limited vs Binding [2026 Guide]

Going through Services Australia to set child support isn't your only option. Parents who can cooperate have the right to make their own arrangement — and in many cases, a private agreement is simpler, more flexible, and better suited to your actual situation.

Do You Have to Use Services Australia?

No. You're not required to register with Services Australia if you can agree privately. Many parents prefer this approach because it allows them to tailor the arrangement to their specific circumstances — for example, splitting school fees separately, accounting for self-employed income more accurately, or avoiding the delay of a formal assessment.

That said, if the other parent won't cooperate or you need enforcement powers, Services Australia's assessment process provides legal backing that a verbal or informal arrangement doesn't.

Option 1: Limited Child Support Agreement

What is a Limited Agreement?

A Limited Agreement is a written document signed by both parents that sets a child support amount. It doesn't require lawyers. The key constraint is that the agreed amount must be at least equal to the annual rate that would result from a Services Australia formula assessment — you can't use a Limited Agreement to pay less than the formula says.

How to Set One Up

Both parents sign the agreement, then either parent lodges it with Services Australia. Once registered, it becomes legally enforceable and Services Australia can collect payments if needed.

How Long Does It Last?

A Limited Agreement lasts a minimum of three years. After that, either parent can end it with 28 days' written notice — at which point the arrangement reverts to a standard Services Australia assessment.

When Does It End Automatically?

• A new Services Australia assessment is made that differs by 15% or more from the agreement amount
• The child turns 18 (or finishes secondary school if still enrolled)
• The child dies
• The parents reconcile and live together for more than 6 months

Limited Agreement — Pros and Cons

Option 2: Binding Child Support Agreement

What is a Binding Agreement?

A Binding Child Support Agreement is more powerful and more flexible than a Limited Agreement. It can set payments above or below the formula amount, cover specific expenses like school fees, medical costs and extracurriculars, and run for any term the parties agree on.

The trade-off is that both parents must obtain independent legal advice before signing. This means each parent must consult their own lawyer separately, who must confirm they understand the agreement and its implications.

How to Set One Up

Each parent engages their own family lawyer. The lawyers draft or review the agreement independently. Once signed, it's registered with Services Australia. Budget roughly $300–$800 per parent in legal fees, depending on complexity.

When Can a Binding Agreement Be Set Aside?

Binding agreements are difficult to overturn, which is by design. A court can only set one aside if there is evidence of fraud, duress, undue influence, or if circumstances have changed so significantly that a child's needs are no longer being met.

Binding Agreement — Pros and Cons

Which Should You Choose?

• Choose a Limited Agreement if: you're on reasonable terms, want to formalise what you already do informally, and payments are at or above the formula rate.
• Choose a Binding Agreement if: you want payments below the formula rate, want to lock in school fees or special expenses, have complex finances, or want a long-term arrangement that neither party can easily walk away from.

If you're unsure what the formula rate would be in your situation, use the calculator to check before deciding which type of agreement suits you.

What Happens if the Other Parent Won't Agree?

A private agreement requires both parents to sign. You cannot force the other parent into one. If agreement isn't possible, you'll need to apply through Services Australia for a standard assessment — or in complex situations, seek a court order through the Family Court.

Can a Private Agreement Cover Extras Like School Fees?

Yes — this is one of the key advantages of a private agreement over a Services Australia assessment. The standard formula doesn't include private school fees, extracurriculars, overseas trips or high medical costs. A Binding Agreement can include any of these explicitly.

See our guide on what child support doesn't cover for a full breakdown of what the standard assessment excludes.

How to Register Your Agreement with Services Australia

Once signed, either parent can lodge the agreement with Services Australia online through myGov, by post, or in person. Services Australia will then use it as the basis for any collection or enforcement if needed.

Keep a signed copy in a safe place. If you need to enforce the agreement later, the registered version held by Services Australia is the official record.