Online auctions look the same on the surface as eBay or any other listing site, but the rules underneath are different, and worth knowing before you bid.
What is a timed online auction?
A timed online auction is an event with a fixed start and end. Each lot sits inside that event with its own closing time. Bids can be placed any time during the window. The highest bidder when the clock hits zero wins.
That's the basic shape. The interesting bits are what happens at the edges.
Bidding 101
The starting bid is set by the seller. You can only bid in bid increments, usually £1 or so on a small lot, more on larger items. The platform won't accept anything below the next valid increment.
You don't need to sit watching the clock. Set a max bid and the system bids on your behalf, one increment at a time, up to your maximum. This is sometimes called "proxy bidding". If someone else's max is higher than yours, they win at one increment above your max. If yours is higher, you win at one increment above theirs.
The actual price you pay is rarely your max, it's whatever the second-highest bidder forced you up to, plus one increment. That's the Vickrey-like quirk of proxy auctions, and why setting a generous max is often a winning strategy: the system protects you from overpaying.
Anti-snipe
In the last 60 seconds of a lot, any new bid extends the clock by another 60 seconds. The clock keeps extending every time someone bids late, until nobody does. This stops the auction being won by whoever has the fastest finger and the lowest latency, and turns the close into a real bidding contest.
If a lot's still extending after the originally-advertised end time, that's normal.
What you actually pay
Three things stack on top of your winning bid:
- Buyer's premium, a percentage added to the hammer price. Typical UK auction houses charge 15–25%. The lot listing shows this before you bid; it's not a surprise.
- VAT, usually charged on the buyer's premium at the standard rate (20%). Some lots are sold under the second-hand goods margin scheme, which means VAT is built into the hammer price and there's no separate VAT line for the buyer. The listing tells you which.
- Shipping, flat or weight-based, shown on each lot before you bid.
So a £100 hammer bid on a lot with 15% buyer's premium and standard VAT comes out to:
Hammer: £100.00
Buyer's premium: £15.00 (15%)
VAT on premium: £3.00 (20% × £15)
Shipping: £4.99
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Total to pay: £122.99
Reserve prices
Some lots have a hidden reserve, a minimum price below which the seller won't sell. If bidding ends without the reserve being met, the lot is marked unsold and may be relisted. You'll see a "reserve not met" badge on the lot while it's below the reserve and a "reserve met" once you've crossed it.
The reserve number itself is hidden so it doesn't tip off bidders to where the seller's pain point is.
"Sold as seen", and what that actually means
Auction lots are typically described in the listing as sold as seen or sold subject to the condition stated. That's an auction-house tradition with some legal weight: it shifts more of the inspection responsibility onto the buyer than you'd expect on, say, Amazon.
For consumer buyers, the Consumer Rights Act 2015 still applies, items must be as described and of satisfactory quality given their condition codes. So a lot described as "untested" and "for parts" can come up dead and you've no comeback. A lot described as "working, tested" that arrives broken is something we'd refund.
What's different to eBay?
Three big things:
- Bids are binding the second you place them. You can't retract. eBay technically also forbids retraction but routinely allows it; auction houses don't.
- No 14-day cooling off period. UK auctions are explicitly exempt from the Consumer Contracts Regulations cancellation window. If you win, you've bought it.
- Faster payment. Most auction platforms charge the saved card automatically on win. You don't sit waiting for a buyer to pay.
That binding-bid bit is the part that catches first-time auction buyers out. Treat every bid like it's signing a contract, because it is. Don't bid on lots you're not sure you want or can't afford.
Getting started on Biddurs
If you've never bid on Biddurs before, here's the shortest path to your first win:
- Sign up at biddurs.com/register. Email verification is required before your first bid.
- Find an event at biddurs.com/auctions, events run daily across themes like Amazon returns, overstock, electronics, fashion.
- Enrol in the event and save a payment card. The card sits in Stripe, we don't see or store it.
- Bid on the lots you want, setting a max if you'd rather not sit watching.
- Win and we charge automatically. Dispatch within 2 working days of cleared payment.
Win multiple lots in one event? Email us within 7 days of winning and we'll combine the parcels and refund the postage difference.
That's it. The clock does the rest.