Technically speaking you can make an offer without any deposit. However, in a number of cases the seller will not accept the offer as another buyer may provide a large deposit giving the seller comfort they are more serious. Generally an agent will request a certain amount around 5% of the purchase price, sometimes higher or lower. However, the size of the deposit should be based around what you have available to pay in your account. There is no point agreeing to a $20,000 deposit if you have $10,000 in your account as your bank will only make loan funds available on the settlement date. The contract will stipulate who you pay the deposit to and you must ensure the funds are in their account (generally the agent's trust account) prior to the due date for its payment.