Contrato (contract): A typical contract runs for one year. Be sure to read the contract carefully and ensure everything is clear. If the contract includes an inventory (dishes, linen, etc.), make sure the items are there when you move in. In addition, check that all electrical appliances and utilities are in working order. Don't take a verbal guarantee that defective items will be fixed later, get it written into the contract or, better still, have it fixed before you agree to move in.
Gastos de comunidad (utilities): Depending on the landlord, utility expenses and community fees may or may not be included in the rent. Community fees generally cover the costs of the doorman, general maintenance and trash collection and sometimes one or more of the utilities. Just be sure to ask which items you will have to pay for individually.
Fianza (deposit): Most landlords ask for a security deposit equivalent to 1 or sometimes 2 months rent if the flat is furnished. Anything more than this should be avoided. You also may be able to negotiate the conditions concerning the return date of the deposit or try to use it to pay the last month's rent. Naturally, it is preferable to get any additional agreement in writing.
Garantías (guarantees): Given that Spain's legal system does not offer strong protection to property owners, it is very common for landlords to ask for additional guarantees. If you are working, a copy of a payslip (nómina) is requested as proof that your monthly salary exceeds the rent. If you are a student, landlords may require a letter from your school to certify you have the necessary means.
Aval bancario (bank guarantee): As a further guarantee, landlords sometimes request an aval bancario. It is essentially a letter of credit from a Spanish bank guaranteeing that if you default on your obligations, the bank will pay whatever is owned for the remainder of the contract.