To bid at an auction, you register with the house before the sale, review and sign the conditions of sale, receive a paddle or online login, then place bids in the auctioneer’s set increments until the hammer falls or you drop out. Winning creates a binding contract, and you pay the hammer price plus a buyer’s premium and any tax within the deadline the house sets. The mechanics are shaped partly by each auction house’s own terms and partly by the Uniform Commercial Code, which gives you specific rights most bidders never hear about.
Inspect the Lots During the Preview
Auction houses hold a preview period before the sale where you can physically examine items. This is your only real chance to check condition, authenticity, and whether an item matches its catalog description. Preview hours run from a few hours to a full business day depending on the auction. Skip the preview at your own risk. Nearly every auction house sells property “as-is,” meaning you accept all defects once the hammer drops. There are no returns.
For higher-value lots like real estate, vehicles, or fine art, this is when you bring in experts: an independent appraiser, a mechanic, or a collector who knows the category. The catalog estimate is the seller’s opinion of value, not a guarantee. Treat it as a starting point for your own research.
Register and Read the Conditions of Sale
You cannot bid without registering first. Registration happens online through the auction house’s website or in person before the sale begins. You will need a government-issued photo ID and contact information. Many houses also require financial verification, especially for higher-value sales.
Financial verification often means a bank letter of guarantee. That is not a balance statement. The bank must irrevocably guarantee payment up to a specified dollar amount, on official letterhead and signed by a bank officer. The letter should name the account holder, include the account number, state the maximum guaranteed amount, and specify an expiration date at least several days after the auction. Without one, most houses will not accept a personal check or wire from a new buyer.
Registration includes signing the Conditions of Sale, the contract that governs the entire transaction. Two clauses matter most. The “as-is” clause means no warranties about condition, provenance, or fitness for any purpose. The buyer’s premium clause tells you the percentage fee the house adds on top of your winning bid, and it can significantly increase your total cost.
Calculating the Buyer’s Premium Into Your Ceiling
The buyer’s premium is a percentage of your winning bid that gets added to determine your total purchase price. Major houses use tiered structures. At Sotheby’s, the premium is 28% on the first $2 million of the hammer price, 22% on the portion between $2 million and $8 million, and 15% above $8 million.1Sotheby’s. What Is a Buyer’s Premium Christie’s charges 27% up to $1.5 million, 22% between $1.5 million and $8 million, and 15% above that.2Christie’s. Financial Information
Smaller regional houses and online platforms typically charge a flat premium between 15% and 25%, and real estate auctions often run lower at 5% to 10%. Whatever the rate, work the premium into your maximum bid before the sale starts. If your budget is $10,000 total and the premium is 20%, your maximum hammer price is roughly $8,333, not $10,000. Forgetting that math is one of the most common mistakes new bidders make.
Know Whether the Sale Is With or Without Reserve
Every auction is either “with reserve” or “without reserve,” and the distinction changes how the sale works. Under the Uniform Commercial Code, an auction is with reserve unless the house explicitly states otherwise.3Legal Information Institute. UCC 2-328 Sale by Auction Most auctions you encounter are with reserve by default.
In a with-reserve auction, the seller sets a confidential minimum price. If bidding does not reach it, the lot is “passed” or “bought in” and no sale occurs.4Christie’s. Reserve Prices at Auction The auctioneer can also withdraw the item at any time before announcing the sale is complete.3Legal Information Institute. UCC 2-328 Sale by Auction Catalogs usually mark the lots that carry no reserve, because those are the exception.
In a without-reserve sale, once the auctioneer calls for bids, the item must sell to the highest bidder regardless of price, as long as at least one bid comes in within a reasonable time. The seller gives up the right to pull the item back.
How the Bidding Actually Moves
Auctioneers do not accept bids in random dollar amounts. They follow a published increment schedule. At Christie’s, bids between $100 and $2,000 move in $100 steps, bids between $5,000 and $10,000 move in $500 steps, and bids between $100,000 and $200,000 move in $10,000 steps.2Christie’s. Financial Information Local houses use similar logic at smaller scales. The schedule is usually in the catalog or on the bidding platform.
Knowing the increments lets you calculate exposure before raising a paddle. If a lot sits at $5,000 and increments are $500, your next bid commits you to $5,500. That precision matters near your ceiling.
Live Sales, Online Platforms, and Absentee Bids
At a live auction you receive a numbered paddle at check-in. Raise it to signal a bid. The auctioneer acknowledges bidders by paddle number and announces the current high bid continuously. Bidding moves fast, and the auctioneer’s chant can be disorienting the first time. If you can, attend a sale as a spectator before your first real bid to get a feel for the rhythm.
Online platforms show real-time prices on a dashboard. You click to bid and the system confirms instantly. Most platforms add a “fair warning” countdown, either a digital timer or a verbal announcement. Some extend the timer by 30 to 60 seconds whenever a last-moment bid arrives, which prevents sniping.
If you cannot attend, most houses let you submit an absentee or proxy bid in advance. You set a maximum, and the auctioneer or an automated system bids on your behalf in the smallest increments needed to keep you in the lead. If nobody outbids your maximum, you win at one increment above the second-highest bid, not at your full ceiling. Double-check every digit before submitting. A typo like $50,000 for $5,000 creates a binding commitment.
Whether in person or online, the sale is legally complete when the auctioneer announces it by the fall of the hammer or by any other customary method.3Legal Information Institute. UCC 2-328 Sale by Auction That moment creates a binding contract between you and the seller.
Your Legal Rights as a Bidder
The Uniform Commercial Code gives bidders two protections most people never hear about.
You can retract your bid at any time before the auctioneer announces the sale is complete. Retracting does not revive any earlier bid, so bidding resets to the last standing offer from another participant.3Legal Information Institute. UCC 2-328 Sale by Auction Doing it in a live room will draw attention and may irritate the auctioneer, but it is your right. Online platforms sometimes restrict retraction windows more tightly, so check the terms.
If the auctioneer knowingly accepts a bid placed by or on behalf of the seller, and the house did not disclose that the seller reserved a right to bid, the winning buyer can either void the sale entirely or take the item at the price of the last legitimate bid before the shill bid.3Legal Information Institute. UCC 2-328 Sale by Auction Some auctions do disclose that the seller or house may bid, in which case the protection does not apply. Read the Conditions of Sale.
Paying, Taxes, and Collecting
Winning bidders receive an invoice shortly after the sale closes, listing the hammer price, the buyer’s premium, applicable taxes, and the total due. Some houses require immediate payment upon conclusion of the sale.5Sotheby’s. Guide for Buyers Global Others allow a short window, typically a few business days. Regional and online houses may give up to seven days. Treat the deadline as hard. Late payment triggers penalties, interest, and in some cases forfeiture.
Most houses prefer wire transfers or cashier’s checks because those funds clear immediately. Personal checks may be accepted if backed by a bank letter of guarantee. Credit cards are often accepted for lower-value purchases with a surcharge. Card network rules cap credit card surcharges at 3% to 4% of the transaction depending on the brand, and some states set lower limits. Debit cards cannot be surcharged. On a large purchase the surcharge alone can run into thousands of dollars, making a wire the cheaper option.
Auction purchases are subject to sales tax in most states. Rates run from zero in Delaware, Montana, New Hampshire, and Oregon up to 7.25% at the state level, and local taxes can push the combined rate above 10%. Since the 2018 Supreme Court decision in South Dakota v. Wayfair, online sellers no longer need a physical presence in a state to collect sales tax, so you will likely owe tax on online auction purchases regardless of where the house sits. Registered dealers buying for resale can provide a resale certificate and avoid the tax at purchase, but must be registered for sales tax in the delivery state.
Pickup or shipping is the buyer’s responsibility. Auction houses set a removal deadline. Major houses like Christie’s offer a free storage period of roughly 30 days after the sale, after which daily storage fees and an administrative charge apply.6Christie’s. Storage and Collection Smaller houses often give far less time and charge steeper daily fees. For items that need shipping, get quotes before you bid. Sending a large painting or piece of furniture cross-country through a specialty handler can run hundreds or thousands of dollars.
What Happens If You Walk Away From a Winning Bid
The hammer creates a binding contract, and the auction house has several remedies when a buyer defaults. The usual sequence: the house contacts you about the missed payment, applies any deposit toward the balance, and if you still do not pay, resells the item. You are liable for the difference between your original bid and the resale price, plus storage, interest, resale expenses, and legal fees.
Financial exposure is not the only cost. Auction houses share information within the industry, and a non-payment record at one house can follow you to others. Online platforms often suspend bidding privileges automatically after a small number of unpaid wins. Never bid more than you can actually afford to pay.