Reserve price vs guide price at auction: how sellers set both

A reserve price is the lowest price you'll let the auctioneer sell your land for, and it stays confidential. A guide price is the figure published to bidders, and in the UK it can't sit far below your reserve: under the Advertising Standards Authority's 2014 ruling, a reserve must fall within a guide range, or within 10% of a single-figure guide, unless the auctioneer updates the guide whenever the reserve goes higher.

So you're not free to set a low guide to draw a crowd and a high reserve to protect yourself. The two have to be set together, and when one moves, the other may have to follow.

What is a reserve price at auction?

The reserve is the minimum price at which the auctioneer is authorised to sell the lot. That's the definition in the RICS professional standard Auctioneers selling real estate, which RICS members must follow. The lot can be sold to the highest bidder at or above the reserve, and the auctioneer cannot sell below it.

The rules around it, as of September 2026:

• It's confidential. The amount is known only to you, the auctioneer, and the auctioneer's staff, unless you instruct the auctioneer to publish it.
• Its existence isn't. The Common Auction Conditions (5th edition, July 2024) say each lot is subject to a reserve unless stated otherwise, and that a reserve may be fixed just before the lot is offered.
• It's set in writing. The RICS standard says reserves, and any changes to them, should be confirmed in writing to you as soon as possible.

In England and Wales, the Sale of Land by Auction Act 1867 requires the particulars or conditions of any land auction to say whether the land is sold without reserve, subject to a reserve, or with a right for the seller to bid. If land is sold "without reserve", it's unlawful for the seller to employ anyone to bid, and the auctioneer can't knowingly take such a bid.

Where the conditions do reserve a right to bid, the Common Auction Conditions let the seller, or the auctioneer on the seller's behalf, bid up to the reserve but never at or above it. Bidders are told in the conditions that every bid up to the reserve may have been made for the seller.

What is a guide price?

The guide is the published price that tells bidders what the seller is likely to accept. The ASA's current advice on auction guide prices and non-optional charges describes a guide price as the seller's minimum expectation, not a valuation. Land can sell well above its guide, and the guide says nothing about what the land is worth.

What are the rules on guide price vs reserve price?

Three sets of rules apply, and they don't say quite the same thing.

1. The ASA ruling (all advertisers). On 23 July 2014 the ASA ruled on property auction guide prices, and CAP issued advice on guide prices in ads for property auctions. Every time a guide price appears, the ad must explain what a guide price is, how it differs from a reserve, and that both may change. Unless the auctioneer routinely updates the guide whenever a reserve is set above it, the explanation must say that the guide indicates the range within which, or for a single figure within 10% of which, the minimum sale price will fall.

2. RICS best practice (RICS members). The RICS professional standard goes further. Its recommended definition is that a published guide is the minimum price the seller is prepared to accept at the date of publication, and that with a range, the minimum acceptable price shouldn't exceed the lower end. If your minimum rises, the guide should be adjusted and republished straight away.

3. The RICS practice alert (April 2025). RICS reminded members that guide figures must reflect the anticipated reserve when they're published, and that setting guides at levels the owner won't accept, to bait bidders, is misleading. Bait advertising is a banned practice under Schedule 20 to the Digital Markets, Competition and Consumers Act 2024, which replaced the Consumer Protection from Unfair Trading Regulations 2008 from 6 April 2025.

Here's what that means for the highest reserve each guide allows. The figures are illustrations, not valuations.

In practice, you agree the guide and the reserve together with the auctioneer, and the ASA ruling sets the outer limit. Ask your auctioneer which approach they follow, because a firm that works to the RICS definition will want your reserve at or below the guide.

How do I decide on a reserve?

The RICS consumer guide to property auctions suggests starting by asking the auctioneer what they'd recommend as guide and reserve. An independent valuation gives you a second view to set against it before you sign.

For that view, look for a RICS Registered Valuer. RICS members giving written valuations must follow the RICS Valuation Global Standards, known as the Red Book, whose current edition took effect on 31 January 2025. Registered valuers are monitored under RICS's Valuer Registration scheme, which checks compliance with the Red Book. For farmland, many rural valuers also hold the FAAV qualification from the Central Association of Agricultural Valuers, awarded after its own written, practical, and oral exams.

A valuer will look at comparable sales of similar land, the land's grade, access, water, and buildings, and any tenancy, overage, or designation that affects value. Our guide to agricultural land valuation for sale explains what drives the figure, and agricultural land prices by region gives the wider context. AgLand doesn't value land or recommend valuers.

Once you have a view of value, the reserve is a separate decision about the lowest sale you'd accept. Things to weigh:

• Your minimum, not your hope. If bids reach the reserve, the auctioneer can sell, and at a traditional auction you're bound on the hammer.
• The guide it forces. A higher reserve means a higher guide, which may put off bidders who'd have pushed the price up.
• Your costs so far. The entry fee and legal pack are spent whether or not the lot sells. See the cost of selling land at auction.
• Tax. Your accountant may want to see how different sale prices change your capital gains tax bill before you fix a floor.
• Executors and trustees. If you're selling for an estate or trust, your solicitor can tell you what evidence you need that the price was a proper one.

Can I change the reserve?

Yes, up to the moment the lot is offered. The RICS standard says the reserve is confirmed at instruction or, with the auctioneer's agreement, at any time before the lot is offered. The Common Auction Conditions allow it to be fixed just before the lot comes up.

The catch is the guide. If you raise the reserve above what the published guide allows, the guide becomes misleading and must be updated. RICS says the auctioneer should publish the change immediately, show it in the addendum, and tell any listing sites they use. Bidders are expected to check for changes, but a late jump in the guide can cost you bidders who've already done their legal work.

Lowering the reserve is simpler, since the guide still covers it, but agree it in writing. The RICS consumer guide suggests asking the auctioneer at instruction how amendments to the reserve and guide are handled.

What happens when bidding stops short of the reserve?

The lot doesn't sell. The RICS professional standard says that where a lot fails to reach its reserve, the auctioneer should:

• say that the lot has not been sold
• not bring the hammer down
• not use wording that suggests bidding has reached the reserve before withdrawing the lot

There is no contract, so you owe the bidders nothing and they owe you nothing. RICS's practice alert says reporting a lot that failed to reach its reserve as sold is likely to be misleading, and a conditional sale should only be marked sold once all its terms are met and the final price is recorded.

After the auction, the auctioneer usually tries to sell the lot at the reserve or higher, as the RICS consumer guide notes, and the highest bidder is the obvious first call. You can accept a lower post-auction offer if you want to, because the reserve only governed the auction itself. Check what commission your terms charge on a post-auction sale before you agree. How a land auction works covers what happens next.

Does the reserve work the same way at a conditional auction?

Mostly, with two differences worth pricing in.

The first difference is certainty. At a traditional auction, a bid at your reserve means a binding sale. At a conditional auction, it means a buyer with a period to exchange, and the RICS professional standard says the risks, including abortive costs, should be set out clearly for both sides.

The second is price. Because the buyer pays a reservation fee on top, The Property Ombudsman has said agents should tell sellers that buyers may adjust their bids to allow for it, under paragraph 4a of its code for residential estate agents. Online timed auctions also have a starting bid, which the auctioneer sets separately from your reserve. Traditional auction vs modern method of auction goes through the trade-offs.

Is it different in Scotland?

The ASA's rules on guide prices in ads apply across the UK, so a Scottish auction guide must be explained the same way. The Sale of Land by Auction Act 1867 does not extend to Scotland, so whether a seller can bid, and how the reserve works, is set by the articles of roup, the Scottish conditions of sale. Some Scottish conditions use the term "upset price". Ask your Scottish solicitor how the articles define it for your lot, and whether it's published.

Next steps

1. Get an independent view of value from a RICS Registered Valuer, ideally one who knows farmland in your area.
2. Ask each auctioneer for their proposed guide and reserve, and which guide-price definition they follow.
3. Decide your true minimum with your accountant, knowing that at a traditional auction a bid at that figure binds you.
4. Agree in writing how the reserve can be changed, and what commission applies to sales before and after the auction.

For the buyer's view of guides and reserves, see our agricultural land auction guide.