Euribor stands for Euro Interbank offered Rate and is the rate on which all mortgage loans are based. The rate you will pay for your mortgage will comprise two elements: Euribor, and Margin. The actual rate you pay will be calculated by adding these two elements together. Spanish banks generally work with the 12 month EURIBOR rate meaning that your rate payable is reset every 12 months according to the prevailing rate at that time.