If the property is new, then your contract will be with the company who is building the property. We deal with many builders and all of them have slightly different terms as to when they would like to receive their staged payments. These terms can be varied a little to suit the individual circumstances of the purchaser if these changes are agreed when the contract is drawn up. All the builders will, however be expecting to receive payments along the following guidelines.
If the property is a resale (i.e. previously owned) your contract will be with the current occupant/owner. With a resale property, a deposit of 3000 to 6000 euros will secure the property, the balance being paid on completion, normally after two months, or sooner if both parties are in agreement to bring the completion date forward. There is no gazumping in Spain, so after accepting your deposit, the seller is legally obliged to sell you the house at the agreed price.