Auction reserve strategy in Australia: setting the number, the vendor bid rules, and when to drop mid-auction

The auction reserve is the most important number in the whole campaign and the one most vendors think about least. Set it too high and the property passes in; set it too low and the auctioneer announces 'on the market' before the room has warmed up. The difference between a strategically-set reserve and an arbitrary one is often 3-5% of sale price on the day. Vendors who treat the number as a tactical decision rather than a hope tend to clear more campaigns and at better prices.

Most of the published guidance on auction strategy is written for buyers. Vendor-side material is thinner, and the parts that matter most (the legal rules around vendor bids, the auctioneer's mid-auction discretion, and the pass-in playbook) usually sit inside an agency rather than on a website. This piece pulls those pieces together.

What an auction reserve actually is

The reserve is the minimum price the vendor will accept on auction day. It is negotiated between vendor and agent, set in writing, and handed to the auctioneer before bidding starts. Buyers do not see it. It can be adjusted up to the start of the auction and, in practice, during the auction itself when the auctioneer confers with the vendor.

• Confidential: never disclosed to buyers, never published in marketing material, and not required to match the campaign price guide.
• The trigger for 'on the market': when bidding reaches the reserve, the auctioneer typically signals the property is now selling unconditionally. The phrase carries legal weight: from that moment, the highest bid wins.
• Movable: vendors can lift the reserve if pre-auction interest is stronger than expected, or drop it mid-auction if bidding stalls just below.

The campaign price guide is a separate document with separate rules, and in Victoria it is heavily regulated under the Estate Agents Act underquoting framework. The reserve sits behind the guide. Most experienced auctioneers aim to have the reserve land near the upper end of the guide so that buyers who turned up with the guide in mind are still in the race when the property goes on the market.

The reserve-setting process

Five inputs feed a defensible reserve. Each one pulls in a slightly different direction.

• Agent appraisal range: the starting point. Worth remembering the agent's commission is aligned with the sale, not the reserve, so the incentive is to land the property at a number that clears, not a number that maximises.
• Comparable sales analysis: recent 90-day sales of similar properties in the same area, adjusted for condition, land size, and timing. The tighter the comparable set, the tighter the defensible reserve range.
• Vendor's walk-away number: the actual minimum below which the vendor would prefer to withdraw and try again later. This is the hardest number for a vendor to set honestly and the most important one to write down before auction day.
• Pre-auction offers: any genuine offer received during the campaign forces a real recalibration. An offer above the agent's lower appraisal often tells the vendor more about the market than the appraisal did.
• Auctioneer briefing: in the final 24-48 hours, the auctioneer recommends a reserve based on campaign feedback: number of inspections, contract requests, registered bidders, and the temperature of conversations at the open homes.

The five inputs rarely land on the same number. The vendor's job is to weigh them, not average them. A reserve set at the comparable median when there are four registered bidders and twenty contract requests is usually too low. A reserve set at the auctioneer's upper recommendation when the campaign has produced two contract requests and a thin inspection list is usually too high.

Vendor bid rules by state

A vendor bid is a bid made on behalf of the vendor (in practice, called by the auctioneer) to set a floor or keep the auction moving. The rules differ by state and the differences matter, because an undisclosed vendor bid is illegal everywhere.

• NSW: vendor bids are permitted under the Property and Stock Agents Act regulations but must be clearly announced as such, typically with the words 'vendor bid' called by the auctioneer. Only one vendor bid is permitted below reserve.
• VIC: vendor bids are permitted under the Sale of Land Act. The auctioneer must announce each one. Up to three vendor bids are allowed and they must occur consecutively, typically at the start, before genuine bidding takes over.
• QLD: similar disclosure rules apply under the Property Occupations Act. Vendor bids are permitted with announcement and are commonly used to set the floor.
• WA: vendor bids are permitted with disclosure under the Real Estate and Business Agents Act.
• SA, TAS, ACT, NT: vendor bid rules vary in detail but follow the same principle. Vendor bids are generally permitted with disclosure.

The legal point sits across all of them: an undisclosed vendor bid is illegal in every Australian state and territory. This is called dummy bidding, and in NSW it carries fines up to roughly $22,000 per offence under the current regulations. Even when properly disclosed, vendor bids are increasingly viewed with scepticism by experienced buyers and buyer's agents, who read a long string of vendor bids as a sign of thin genuine demand. Some agents in the inner-Sydney and inner-Melbourne markets now advise vendors against using them at all on hot stock.

When to drop the reserve mid-auction

Three patterns recur, each with a different right answer.

• One bidder stops just below reserve: if competition is genuinely thin and the standing bidder is the actual buyer at the price, dropping the reserve to capture the sale is usually better than passing in. The standing bidder's next visit to a comparable property is at least a week away.
• Two bidders both stop short: a small drop to put the property 'on the market' can re-energise the room because each bidder now knows the next bid is the winning bid, not a step toward a private negotiation. Vendors with a fixed walk-away number should pre-commit to not dropping below it, and the auctioneer should know that number going in.
• Bids stall 10%+ below reserve: when the gap is large and there is no second-bidder tension, dropping is rarely the right call. The property is over-anchored. Passing in and negotiating post-auction usually produces a better outcome than chasing the room down to a price that signals weakness.

The pass-in scenario

If bidding stops below the reserve and the vendor does not drop, the property passes in. In practice the highest bidder gets exclusive negotiation rights for a short window, typically 24-72 hours depending on state and agency practice, before the property goes to private treaty. Historical agency data puts roughly 30-40% of passed-in properties under contract within a week, with the balance moving to a longer private-treaty campaign or being relisted in the next auction cycle.

Passing in is not a failure. It is a decision to take the optionality of a slower negotiation over a price the vendor has already decided is too low. The mistake is the opposite: dropping the reserve to capture a sale at a price that, in the cold light of the following week, the vendor would have walked away from. Writing the walk-away number down before auction day is the single cheapest piece of self-protection in the campaign.

Pre-auction offers

Buyers sometimes submit pre-auction offers in the final week, either to take the property off the market or to force a price discovery before the room shows up. The decision is rarely obvious.

• Pros of accepting: locks in a buyer at a known price, eliminates the auction-day execution risk, and frees the vendor from the public performance.
• Cons of accepting: foregoes the bidding-war upside if the auction would have produced two motivated underbidders, and sets a public floor for any subsequent campaign if the deal falls over.
• Rule of thumb: accept pre-auction offers at or comfortably above the reserve. Below reserve, decline politely, acknowledge the interest, and invite the buyer to register and bid on the day.

A worked Sydney example

Sydney 3-bed house, agent campaign range $1.40M to $1.55M. The auctioneer recommends a reserve of $1.48M on the back of 22 inspections, five contract requests, and three registered bidders. The vendor's private walk-away is $1.42M; below that the plan is to relist in spring.

Auction day: opening bid $1.35M (a vendor bid, properly announced), two genuine bidders work the price up in $10k increments to $1.46M and then both pause. The auctioneer pauses, confers with the vendor, and the vendor agrees to drop the reserve to $1.46M. The property is announced on the market, one more bid takes it to $1.47M, the hammer falls.

Outcome: sold at $1.47M against an original reserve of $1.48M. A $10k haircut to capture the sale on the day. Net to vendor still well above the $1.42M walk-away.

The counterfactual matters. Suppose the vendor had held firm and passed the property in at $1.46M. Post-auction negotiation begins immediately. Historical agency data suggests roughly 35% of passed-in properties at this price point sell within seven days, usually at or just above the highest bid. Run the expected value: $1.47M certain on the day versus an expected sale price of roughly $1.46M with a 0.85 probability of equivalent execution within fourteen days (the 0.85 accounts for the higher-bidder walking, the second bidder lowballing, and the campaign cost of a delayed close). That comes to an expected $1.241M from the pass-in path on a risk-weighted basis, or alternatively a 30+ day wait for a fuller second campaign. The $10k reserve drop captured certainty worth materially more than the optionality of passing in.

Two checks worth running before you commit to any reserve strategy: the after-tax outcome on the CGT calculator (the main residence exemption may or may not cover the gain in full) and the cost side on the selling cost calculator, because agent commission, marketing, and conveyancing all come out of the headline sale price.

What to brief the auctioneer on

A good auctioneer asks for all of this. A vendor walking into auction day should have it ready regardless.

• The reserve, in writing, with the agent and auctioneer as co-signatories.
• The private walk-away number, separately, with explicit instruction not to drop below it.
• A view on vendor bids: how many, at what levels, and whether to use any at all given the registered-bidder count.
• A decision tree for the pass-in scenario: who has authority to accept a post-auction offer, what the minimum acceptable post-auction price is, and how long the exclusive negotiation window runs.
• A view on pre-auction offers: the price above which the vendor will sell prior, and the standard polite rejection script for offers below that.

Where auction strategy sits in the broader sale decision

Choosing auction in the first place is a separate decision from setting the reserve. The trade-offs are covered in the companion piece on auction versus private treaty, and the cost structure of either path is set out in selling agent commissions. Vendors weighing whether to skip the agency entirely should read selling privately without an agent before signing anything. For the legal layer around the contract handed to bidders on the day, the vendor disclosure piece covers the Section 32 and Form 1 requirements that have to be in place before any bid is legally enforceable.

On Burbfinder, suburb pages surface recent sale prices, days on market, and clearance rates for the area, which are the inputs that turn an auctioneer's recommendation into a defensible reserve. A reserve set against the actual local data has a different character from a reserve set against an appraisal. The vendor who does the work to know the difference rarely regrets the hour spent.