Having found an estate agent, and a property you wish to buy, your first step is to sign a Contrato de Promessa de Compra e Venda - a contract of sale. This is a legally binding document which is drawn up by a notary. At this stage, it is normal to pay a 10-12% deposit on the property, which will be forfeit should you drop out of the sale. If, however, the vendor drops out of the contract, the vendor is obliged to repay you twice the deposit. As a buyer, you must obtain a Fiscal Number from the local tax office.
A date will be set for the final signing of the contract - the Escritura de Compra e Venda. This is usually three or four weeks from the initial sales contract. This time period give your lawyer time to check the property for any outstanding mortgage payments or unpaid taxes outstanding on the mortgage, and to ensure everything is legally in order.
The signing of the final contract, and thus the property transfer taking place, is subject to the payment of a municipal payment called an IMT (Imposto Municipal sobre Transamissoes). The payment is made at the local tax office. The actual amount depends on the price of the property, based on a percentage by "platforms" on the final value. Any estate agents commission is paid by the vendor; the level of commission is not fixed and can vary from agent to agent.
As soon as the final contract of sale is signed, your lawyer will register your details with the Land Registry.