Spanish law heavily favors the tenant over the landlord, as is the case in most of Europe.
There are no clear standards for furnishings; unfurnished properties may be completely bare, have only basic kitchen appliances, or include a few pieces of furniture left by the landlord. Likewise, furnished properties can be either comprehensive, including kitchen items, or very basic—so if you view the property while the previous tenant is still in residence, make sure you’re very clear about which pieces of furniture are staying.
When it comes to signing a rental lease, if you sign for less than a year it’s a short-term contract (contrato de arrendamiento de temporada) and you will have to move out when it ends (unless the owner wants to renegotiate).
If your lease is longer than one year, it is a long-term contract, or arriendo de vivienda, where the owner has to accept annual renewals up to a three-year period. In most cases you will have to pay a deposit of one month’s rent which may be held by the landlord or in an escrow account.
In most cases, the tenant pays for the utility costs (gas, water, electricity, internet). The property tax (IBI) and community fees (Cuotas de Comunidad de Propietarios) are normally the landlord’s responsibility, but it can be agreed otherwise if both parties accept.