When the price and conditions are agreed Spanish Estates will draw up a reservation contract that will be signed by both parties and close the deal.
The buyer will pay a deposit of, normally, 6000 Euros which will guarantee that the vendor withdraws the property from the market and stop offering it to other potential buyers.
In the reservation contract it will state the time for completion. If the completion is within 30 days the next step is normally to sign the deed in front of a public notary. If the agreed completion will be later than 30 days the praxis is to sign a private purchase contract and pay 10% of the price (minus the deposit already paid).