Buying a home at auction in New South Wales: the bidder's rules

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Kooky

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A private sale in New South Wales gives a home buyer a short safety net after the contract is exchanged. An auction gives none. The NSW Government's page on buying property at an auction, managed by NSW Fair Trading and last updated on 8 July 2026, puts the consequence in plain terms: the highest bidder when the hammer falls must sign the contract immediately, so a bidder has to be sure beforehand that the purchase can go ahead.

This guide follows that page and the regulator's related pages from the buyer's side of the rope. It covers what has to be settled before auction day, what an agent may say about price, how a bidder registers and with which documents, what the auctioneer is and is not allowed to do, the deposit and the contract at the fall of the hammer, and the two routes around the auction itself: an offer made beforehand and a negotiation after the property is passed in. Everything here is the law and official guidance of New South Wales only. Other Australian states and territories run auctions under their own rules.

NSW Government page on buying property at an auction, last updated 8 July 2026, and NSW Fair Trading's Bidder's guide, last updated 22 September 2025.

How an auction differs from a private sale

The NSW Government describes an auction as a public sale of a property, run by a real estate agent acting as auctioneer. Bidding is done in the open. The seller, called the vendor, nominates a reserve price, which the same page says is usually neither advertised nor disclosed. If bidding meets or passes the reserve, the property sells at the fall of the hammer.

In a private sale, known in New South Wales as a sale by private treaty, the NSW Government's page on contracts and deposits explains that, after contracts are exchanged, a buyer of residential property has a cooling-off period of five business days. Withdrawing during that period costs 0.25 per cent of the purchase price, which the page expresses as A$250 for every A$100,000.

None of that second stage exists at auction. The cooling-off period, according to the contracts and deposits page, does not apply to a property bought at auction, nor to a contract exchanged on the same day as an auction after the property has been passed in. The auction page adds what follows from that: a successful bidder must be ready to exchange and to complete the purchase, and one who is not stands to lose the deposit and may be liable for the vendor's losses as well.

A worked example shows the size of the gap. Assume a home sells for A$1,200,000. A private treaty buyer who withdraws inside the cooling-off period pays 0.25 per cent, which is A$3,000 (twelve lots of A$250). An auction buyer who has paid the usual 10 per cent deposit has A$120,000 at stake, forty times as much, before any claim for the vendor's losses is counted. The figures are illustrative; the rates are those given on the NSW Government pages.

What has to be done before auction day

Because the purchase is final at the hammer, every check a private buyer could finish during cooling-off has to be finished before the auction. The NSW Government's auction page lists the preparation under financial readiness: confirm the maximum borrowing with the lender, stamp duty included; inspect the property and obtain professional building and pest reports; for a strata property, review the strata reports; and have the contract reviewed by a solicitor or a licensed conveyancer.

The contract is available early for a reason. The contracts and deposits page says a residential property cannot be put on the market until a contract of sale has been prepared, so a bidder can ask for it as soon as the property is advertised. According to the NSW Government's page on the steps to selling a property, the contract must include a copy of the property certificate, the registered plan and dealings, a drainage diagram, a section 10.7 zoning certificate and a statement of the buyer's cooling-off rights. The same page says that where a required disclosure document is missing, the purchaser may rescind within 14 days of exchange, unless settlement has already taken place.

A bidder who wants a term changed has to raise it before the auction, and through the right channel. The contracts and deposits page is explicit that only the buyer's legal representative can change the contract, and that a real estate agent cannot.

The auction page also raises land tax. Outstanding liabilities of the seller may need to be paid at settlement, so the page tells buyers to check for land tax charges before the auction and to request a clearance certificate from the seller before the sale is finalised.

What the agent may say about the price

A bidder walks into an auction without knowing the one number that decides whether the property sells. The NSW Government's page on making an offer says agents do not have to disclose the reserve price or the estimated selling price, and that for an auction the reserve may not even be set until auction day. The page on selling adds that the seller must instruct the agent of the reserve in writing before bidding begins.

What an agent does say is regulated. If a buyer asks what the agent expects the property to sell for, the making an offer page says the answer cannot be lower than the estimated selling price written into the agency agreement, which is the agreement between the vendor and the agent. Stating a lower figure is underquoting. The page calls it an offence for which agents can lose their fees and commission and be fined up to A$22,000.

The same page says that a final price above the advertised figure does not by itself show underquoting, because competitive bidding can push a price up. It notes that new underquoting laws are expected to start towards the end of 2026; their detail was not set out on the page read for this guide.

Registering to bid, and the documents accepted

Nobody may bid at an auction of residential or rural property in New South Wales without registering first. NSW Fair Trading's Bidder's guide, last updated on 22 September 2025, says a bidder must give the selling agent a name and an address and show proof of identity. The agent enters the details in a document called the Bidders Record and hands over a bidder's number, which must be displayed when bidding and returned to the agent after the auction. Agents must give every potential bidder a copy of the Bidder's guide before the auction, according to the NSW Government's auction page.

Registering carries no commitment. The guide says it gives the right to bid and no obligation to do so.

The guide accepts identity in one of two ways:

• One document showing both name and address, issued by a government or a financial institution. The examples given are a driver's licence or learner's permit, a vehicle registration paper and a council rates notice. The NSW Government's auction page adds the NSW photo card.
• Two documents together. One shows the bidder's name and comes from a government or a financial institution: a passport, a Medicare card, an ATM or EFTPOS card, a credit or store card, a birth certificate or citizenship papers. The other shows the address: a utility bill, a rental agreement or a statutory declaration stating the address.

Two limits apply to how the documents are shown. Certified copies are not accepted. Documents may be produced electronically, for instance as an emailed photo or PDF, if the agent consents, but holding them up to the camera on a video call is not permitted.

Registration can happen at any time before the auction, including at an inspection, or on the day itself until the auction ends. A bidder who registered in advance must still show proof of identity on auction day to collect the number. Someone who arrives after bidding has begun is told by the guide to find the agent quickly and, if a bid is needed at once, to raise a hand so the auctioneer knows a bid is intended. Bids from that person can be accepted only once the bidder's number is in hand.

Bidding for someone else, and who sees the record

Couples and other joint buyers need only one registration. The Bidder's guide says that where people are buying together, such as spouses or partners, one of them registering is enough.

Bidding for another person is different. The guide requires a letter of authority, and says the rule covers telephone bids made on someone's behalf as well. For a person, the letter must give that person's name, address and proof-of-identity number, with a driver's licence number as the example. For a company, the letter must be on company letterhead, and the company's Australian Business Number is recorded as its proof of identity. NSW Fair Trading's page for agents on auctions adds two exceptions: someone holding a power of attorney does not need the letter, and a licensed buyer's agent may show the agency authority instead.

There is a reason to get this paperwork right that goes beyond admission to the auction. Among the conditions listed on the agents' page is one that treats a bidder as a principal, meaning the person buying in their own right, unless written authority was given to the auctioneer before bidding. A friend or relative who bids as a favour without that authority is, on the wording of the condition, taken to be bidding in their own right.

The record itself is closed. The guide says the agent must not show the Bidders Record to anyone, the property's owner included; only an authorised person from NSW Fair Trading may view it. The agent must store it securely and may not use the information for any other purpose, and needs only to sight identity documents, not copy them. The agents' page says the record is kept for at least three years.

What the auctioneer may and may not do

An auction of residential property or rural land runs under conditions set by the Property and Stock Agents Regulation 2022, which NSW Fair Trading names alongside the Property and Stock Agents Act 2002 as the law governing auctions. NSW Fair Trading's page for agents lists twelve of them, and says they must be displayed legibly, in English, in a conspicuous place where the auction is held, with enough copies for the people attending. Notices on collusive practices, on dummy bidding and on what is required of the successful bidder must be displayed too. Auctions may be held in person or electronically.

Read from the bidder's side, the conditions give the auctioneer four powers:

1. To bid once for the seller. One vendor bid is allowed, and no more.
2. To refuse a bid. The auctioneer may decline any bid considered not to be in the vendor's best interests.
3. To settle disputes. The auctioneer is the sole arbiter of a disputed bid, and the decision is final.
4. To close the bidding. No bid can be made or accepted after the fall of the hammer.

The vendor bid is the one most likely to affect what a buyer pays, and it comes with conditions. According to the agents' page, it can be made only if the auctioneer announced before the start that a bid may be made for the vendor, and the auctioneer must state clearly, when making it, that the bid is the vendor's.

There is one exception to the single bid. A co-owner, an executor or an administrator, or a person bidding for one of them, may bid more than once, but only if the auction conditions say so, the auctioneer announces it before bidding starts and the bidder registration number of each such person is announced before the auction.

The limits on the auctioneer are as firm as the powers. The agents' page says an auctioneer must not accept a bid from a person who is not registered or has no bidder's number, and that inventing bids is an offence. A bid taken from an unregistered person is nonetheless treated as valid; it is the auctioneer who answers for it, with possible disciplinary action and a fine of up to A$11,000.

Dummy bidding and collusion: rules that bind bidders too

Not every auction offence belongs to the people running the sale. The NSW Government's auction page says it is illegal to make dummy bids at an auction, and gives the court penalties: up to A$55,000 for a person who makes, arranges or requests dummy bids, and for an agent or auctioneer involved, and up to A$110,000 for a corporation.

Collusion runs the other way, towards a lower price, and it is the offence a group of buyers can commit. The agents' page describes it as abstaining from bidding, bidding only to a limited extent or otherwise preventing free and open competition as the result of a collusive practice. An arrangement between two would-be buyers that one will stay silent so the other buys cheaply falls within that description. The auction page sets the maximum penalty at A$55,000 for an individual and A$110,000 in any other case, corporations included.

The fall of the hammer: contract and deposit

The NSW Government's auction page describes the last seconds of an auction this way: after final bids are called, the auctioneer counts down, no bids are accepted afterwards, and the highest bidder is legally obliged to sign and exchange contracts. The conditions on the agents' page say the highest bidder is the purchaser, subject to the reserve, and that the purchaser signs the sale agreement as soon as practicable after the fall of the hammer. The successful buyer's name must be given to the auctioneer as soon as possible.

The deposit is paid there and then. The auction page gives it as usually 10 per cent of the purchase price. The page on selling a property adds a qualification that matters to a buyer short of ready cash: the 10 per cent applies unless a lesser sum or a deposit bond was agreed before the auction. It gives 5 per cent as an example of a lesser sum. The making an offer page speaks of having the 10 per cent ready by bank cheque or deposit bond. The point common to all of them is timing: any variation is agreed with the vendor's side before bidding, not after the hammer.

A worked example, using the same assumed price of A$1,200,000: a 10 per cent deposit is A$120,000, leaving A$1,080,000 to pay at settlement. Had 5 per cent been agreed before the auction, the split would be A$60,000 on the day and A$1,140,000 at settlement.

According to the contracts and deposits page, settlement usually takes place about six weeks after exchange, and the page on selling notes that the parties may negotiate a different period. Settlement is electronic: the buyer must use a lawyer or licensed conveyancer who subscribes to an Electronic Lodgment Network, and cheques and paper documents are no longer required.

When the property is passed in

Not every auction ends in a sale. Where bidding stalls below the reserve, the NSW Government's auction page says the auctioneer privately asks the vendor whether a lower price would be accepted. If the bids still fall short, the property may be passed in or withdrawn.

For the highest bidder this is an opening. The auction page says that bidder generally has the first opportunity to negotiate with the seller. The word is "generally", and the selling page describes the vendor's position more broadly: after a property is passed in, the seller can negotiate with interested bidders or re-list it. Being the highest bidder gives a place at the front of the queue, on these pages, but no right to buy.

The trap is the calendar. A deal struck on the footpath an hour after a failed auction feels like a private negotiation, but the contracts and deposits page says cooling-off does not apply to contracts exchanged on the same day as an auction after the property is passed in. A buyer who exchanges that afternoon is as firmly bound as one who bought under the hammer. The pages read state the exception for the day of the auction only; they do not spell out the position for a contract exchanged on a later day, which is a question for the buyer's solicitor or conveyancer.

Buying before the auction

A property advertised for auction can still be bought beforehand. The NSW Government's auction page says the vendor may consider pre-auction offers, made through an agent, and that the negotiation is the same as for a private sale.

According to the making an offer page, an offer may be made verbally or in writing. The law requires the agent to pass genuine offers on to the vendor unless the vendor has instructed otherwise in writing, and agents must pass on further offers until contracts are exchanged.

Two features of private negotiation therefore come with a pre-auction offer:

• The expression of interest deposit. After an offer, a buyer may be asked for an initial deposit. The page says it does not take the property off the market, that a seller or agent can accept as many of them as they like for one property, and that it is refundable. Before taking it, the agent must give written information that the vendor is not obliged to sell, the buyer is not obliged to buy and the money is refunded if no contract is entered into, and the buyer must sign a statement confirming this was received and understood. If someone else enters a contract for the property, the agent must refund the amount within 14 days.
• Gazumping. This is the page's word for an offer accepted at an agreed price and then lost to another buyer. Neither the agent nor the seller is obliged to compensate a gazumped buyer for legal, inspection or finance costs.

The cooling-off period is where a pre-auction purchase can come to resemble an auction one. The contracts and deposits page says a buyer can waive the period by giving the vendor a 66W certificate, and the selling page describes the waiver as made by a certificate signed by the buyer's lawyer or conveyancer. That page also says it is possible that a vendor will only accept a buyer's offer if the cooling-off period is waived. Only the purchaser can waive it, according to the making an offer page. Where a vendor makes the waiver a condition of selling before auction, the buyer is committed from exchange, as under the hammer.

An auction compresses a property purchase into one moment. Everything a buyer would normally check afterwards has to be checked before the first bid.

What the official pages leave open

Several points sit outside the pages this guide relies on. They cite the Property and Stock Agents Act 2002 and the Property and Stock Agents Regulation 2022 by name, without section numbers, and state penalties as dollar maximums. They do not say who holds the deposit, how a deposit bond works or what happens if settlement is late. They describe auctions held electronically as permitted, without setting out how registration and the display of a bidder's number operate online beyond the rule that identity documents cannot be shown over a video link. And the underquoting laws expected towards the end of 2026 had not been described in detail on the page that announces them.

Kooky, from Shaka

Kooky edits Agents Estate and builds Shaka, the payment router he made for real estate professionals. One payment comes in, and every agent, agency and party in the deal receives their signed share on closing date.

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