Properties in Spain are generally offered based on buyer's cost. You must count with the following percentages and amounts;
10% VAT on new buildings is calculated; if you buy from a developer there is a 1.5% stamp duty on top. A percentage of 10% tax is currently calculated at existing buildings, over the official value, which is declared at the notary.
After the deed is been signed at the notary, it is registered in the Land Registry. Only then the sales transaction is complete. For these two items you should count approximately 1.5% of the purchase price.
Property tax: is a local tax on your real estate, to be paid every year. The percentage is determined for each municipality. On the Costa Brava and Barcelona it is about 0.2-0.4% calculated on the cadastral value of the property. That value (land registry) is actually lagged behind the price movements of the last few years and is still far below the actual value. In case of a house of 300 000 euro’s, you should count with a sum of around 1,250 euros per year.
If you buy a house within an urbanization or complex with communal facilities, you are automatically a member of the Association of homeowners. The amount determined annually what each has to comply, is according to the ownership share of the plot or the apartment. These costs are generally for things like maintenance of private roads, common "green zones", insurance, possibly maintenance of pool, elevator, liability, administration etc.