The short answer
In NSW a written contract is mandatory for work over $5,000, in South Australia at $20,000 and above, and in Western Australia home building contracts must be in writing and signed by both parties. The ACT does not require one but recommends it. Get one anyway for any job that matters.
General information from government pages checked on 11 November 2026, not legal advice. We have not confirmed the rule for every state, so some are left to the regulator.
What each state says
Only rules we confirmed on a government page are listed.
- New South WalesA written contract is mandatory for work exceeding $5,000.
- Western AustraliaContracts must be in writing and signed by both parties.
- South AustraliaYou must have a written contract if the domestic building work is worth $20,000 or more.
- TasmaniaThe Residential Building Work Contracts and Dispute Resolution Act 2016 applies to work priced at $20,000 or more.
- Australian Capital TerritoryACT law does not require a written contract for residential building work, but the government recommends one.
- VictoriaConsumer Affairs Victoria tells homeowners to compare at least three written quotes and says builders must be registered for work over $10,000.
What a good written contract includes
- the tradie's business name, address and licence or registration number
- a clear description of the work and the materials
- a fixed price or a clear way of working out the price
- a start date, a finish date and what happens if they change
- a payment schedule with a deposit inside the legal limit
- how changes are priced and approved in writing
Common questions
Do I need a written contract for a small job?
It depends on the state and the price. Even where it is not required, a written quote with the scope and price protects you.
Does the ACT require a written contract?
ACT law does not require one for residential building work, but the ACT Government recommends one.
Sources
- NSW Government: choosing the right tradesperson or builder, checked 11 November 2026
- Building and Energy WA: building or renovating your home, checked 11 November 2026
- SA.GOV.AU: builder responsibilities, checked 11 November 2026
- Residential Building Work Contracts and Dispute Resolution Act 2016 (Tas), checked 11 November 2026
- ACT Planning: hiring a builder, checked 11 November 2026
- Consumer Affairs Victoria: deposits and payments, checked 11 November 2026