To determine which are the best tanks that can access, to say the simplest way, where should we put our money, we have to take into account various variables beyond the rate of interest. Or, better said, according to the form of the interest rate. We are going to give a simple example. We have two brochures, from two different banks, each with an offer: the first interest rate is 2% and the second of 4%. At first glance it would seem that there is no doubt, the best reservoir is the second Bank. However, may not be what we need and the first suits us more since the interest rate on the other is growing. That is, that as we are acquiring products offered by the Bank (by entering more money, the home insurance) interest rate will increase to 4%, but it may be, that the base type is 1.5%, half a point below the other option. The question is now forced: what interests us the most? What deposit is best for us? We also have to look very carefully at the rate by early cancellation (if you have one) because if we believe that we will need the deposited money before the end of the contracted period the amount of the said fee can leave us without the benefit of the interest. The interest rate and the fee for cancellation are two factors to consider, and although not the only, maybe the most important.