Public Surplus uses three auction formats:

• Simple Auctions - Simple auctions limit the auction to a single item or lot of items. The highest bidder wins the item. Some auctions use a reserve price - an unlisted price that must be met before anyone can win the auction. If the reserve price is not met prior to the auction end, the seller is not obligated to sell the item.
• Dutch Auctions - Dutch auctions allow multiple items to be sold under one auction. Bidders can specify a price and quantity of items they want to purchase. If there are more items requested than available, the highest bidder will receive their full quantity before the other requests are filled.
• Undivided Auctions - Undivided Auctions start with a fixed price amount for a percentage of the item to be sold. Bidders will win by offering the percentage they are willing to get for the current price in a decreasing way. If a limit percentage set by the agency during the auction creation is reached, bidders will have to compete with offers for the price they are willing to pay for the current percentage (as in simple auctions).
• Reverse Percentage Auctions - This auction sets a fixed purchase amount and a starting percentage, which represents the interest rate that the winner of the auction will charge to the person who defaulted. Buyers bid to compete for the lowest interest rate they can offer.