Nowadays many people have resorted and many others will resort to mortgages in order to achieve the dream of being able to acquire their own home, so it is good to know more fully the conditions that they arise from mortgages, to make so you can make the most to loans mortgage and to the greatest extent possible avoid paying more than you need, in such a way in the present article speaks about a point of great importance within we mortgage loans and IRPH or reference indices of mortgage loans, which will be different modalities applied by the banks when it comes to using the interests and updates that they have with the passage of time and movements that occur and to vary the conditions of the interests. Speaking of the IRPH, is this referring to various types of indexes, which are a particular type of percentage by means of which the banking entities update the interest rate on a mortgage that has the condition of being of variable interest rates. The IRPH to vary each month, must be published by the central bank in each monthly period, which in the case of Spain will be the Bank of Spain, Act to undertake through an average of different offerings in the mortgage market are registered by both banks and savings banks. Within the group that is part of the IRPH, the most common and most widely used is the EURIBOR, which I am replacing the MIBOR, which is the interest rate that applies between financial institutions present in the area of European currency exchange that made loans between them. Apart from the EURIBOR, there is also the ECSC, interest rate which has been created by the Spanish Confederation of savings banks, which is determined by the personal loans and those loans mortgage they are formalized within the savings banks. A point of great importance within the IRPH, is to distinguish that there are 3 different modes: the IRPH of banks: in this case the percentage is the average obtained from the types of interests of the mortgage loans that possess a higher term three years and which have been granted by banks during the month. IRPH savings: in this case is handled a system similar to the present to the IRPH of banks, with the difference that here is not taken into account loans made by banks but by the savings banks. IRPH set entities: in this mode the average is taken based on both average, i.e. the banks and savings banks. It is possible to also use as IRPH rate public debt or semi-annual yield of Treasury bonds.