Rules for offers, auctions and buying off the plan

The way a home is offered for sale will determine how you should prepare for the purchase.

Making an offer

Most people buy their home through a private treaty sale – where a property owner accepts the amount of money a buyer offers.

buyer's information notice (form R3) (39.7 KB PDF) must be available to potential buyers during open inspections.


Each offer must be in writing and signed by the potential buyer. The agent must tell the seller about an offer within 48 hours.

Potential buyers aren’t told about other offers. The seller can accept a higher offer without giving you the opportunity to negotiate.

A holding deposit of up to $100 can be requested. This is kept in trust and will be returned if the offer isn’t accepted.

Withdrawing an offer

The buyer will need to complete a cooling-off notice to withdraw. This must be delivered to the seller or their agent by:

  • registered post
  • fax
  • in person.

You should get legal advice before withdrawing from the sale after the cooling off period expires.

Contract of sale

Make sure any conditions are included in the contract before you sign it. Once a contract is signed by the buyer and the seller it is legally binding.

Examples of conditions can include:

  • The offer will be withdrawn if the seller doesn't sign the contract by a certain date.
  • A satisfactory building inspection report must be received.
  • The buyer is able to obtain satisfactory finance.

Make sure the condition is clear. A solicitor or conveyancer will be able to advise about the wording.

Cooling off periods

In many cases, the buyer is entitled to a cooling off period of two business days. This starts when you receive the vendor's statement - What is included on a vendor's statement - or from the date the contract of sale was signed, whichever happens last. This gives you the chance to withdraw from the sale without being held legally responsible.

The buyer will need to complete a cooling-off notice to withdraw. The vendor’s statement (form 1) outlines:

  • the buyer’s cooling off rights
  • the exceptions that apply
  • how to deliver the cooling off notice to the vendor or their agent.

You should get legal advice if you want to withdraw from the sale after the cooling off period expires.

The deposit must be paid once the cooling off period has expired. This money is held in trust until settlement.


registered auctioneer must conduct all property auctions.

A reserve price – the lowest amount the seller is prepared to accept – must be set in writing before the auction but it is not shared with bidders. The set reserve price can be changed by the seller.

The successful bidder is expected to sign the contract of sale and pay the deposit straight after the auction. There is no cooling off period so it’s important to be prepared.

Before the auction

Make sure you prepare by:

  • reading the vendor's statement (form 1). The statement is available:
  • checking that any building inspections you have arranged are complete and you are aware of any issues
  • checking that property valuations required by your bank are complete
  • arranging building insurance for the property - cover note
  • registering to bid.

Registering to bid

All potential bidders must register before the auction. However, the auctioneer could choose to pause the auction so someone who arrives late can register.

Bidders and anyone bidding on their behalf must show ID. The agent can’t keep or make a copy of ID without consent.

If someone will bid on your behalf, they must show a document - signed by you - to prove they can bid for you. An incorporation certificate is needed if someone is bidding on behalf of a company.

A person intending to place a bid must not hinder, harass or prevent another bidder from placing their bid. This carries a fine of up to $20,000.

On the day

We recommend you read this information:

The agent must record each bid as it is made and who placed it. This written record must also include the outcome of the auction.

Vendor bids

The seller can make up to three vendor bids. These must be lower than the reserve price. The auctioneer must announce vendor bids as they are made.

Dummy bids

Dummy bidding is when someone poses as a genuine bidder to increase the price. This carries a fine of up to $20,000.

Paying the deposit

The deposit amount is negotiable and can be as much as 10% of the sale price.

A lower amount can be negotiated before either:

  • the auction
  • a bank guarantee is arranged.

The seller’s agent must place the deposit into a trust account until the settlement date.

Buying off the plan

When you buy a property before it is built - based on the developer’s designs - you are buying off the plan.

A set number of properties might need to be sold before building begins. So, timeframes given by the developer could change.

A deposit is normally paid when the contract is signed with the balance due when the property has been completed.

The contract

Your contract is legally binding once you and the developer sign it. Read it carefully as there could be conditions in the contract that will affect your rights.

Before you sign

You should ask about:

  • making changes to finishes such as paint colours, appliances or flooring
  • your rights if:
    • development approval isn’t given
    • the house isn't completed on time
  • what changes can be made to the design after the contract is signed
  • who is responsible for repairing defects after the home is finished
  • visits to the construction site while your house is being built
  • how you or the developer can cancel the contract
  • any additional costs.

Things to consider

Visit the land your house will be built on and check the size, location and aspect as designs could change after the contract is signed.

If the property will be part of a group, ask if it will be strata, community or Torrens title and check how this will affect you. For example, are pets allowed?

Keeping copies

Always keep a copy of:

  • documents you sign
  • promotional material used by the developer
  • the house designs and plans
  • letters sent to you by the developer or related to the construction.

Rent-to-buy schemes

If you rent-to-buy a home, the property is purchased in instalments. You don't legally own the property until settlement, which happens once all the instalments are paid. In this state, only the South Australian Housing Authority (SAHA) can legally offer rent-to-buy housing options.

There are currently no SAHA properties offered in South Australia.

Seek independent legal and financial advice before signing a contract to make sure you understand all the risks related to rent-to-buy schemes. For example, there is a risk of losing the payments you have already made if you can no longer afford the rental payments.

Most rent-to-buy schemes are not legal in South Australia.

Contact CBS

Online: Contact CBS

Phone: 131 882

GPO Box 1719
Adelaide SA 5001

Related information

On this site

Engaging professionals


It's about the house - CBS

Assessing the suitability of a property (115.5 KB PDF)

For an alternative version of a document on this page contact Consumer and Business Services

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Page last updated 21 November 2023

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