Just be very careful my husband has just looked into it and it can turn out to be much more expensive in the long run. Yes, there is normally a charge, each bank differs. In our case with Banco Popular we would loose our lower interest rate and the period was only for a year and would not only be a higher interest rate but a higher repayment figure. I seriously suggest you make an appointment with your bank manager as it is not a step to be taken lightly as you could end us being worse off than before - it is not the same as interest only in the UK. We ended up looking at some loans we had with them and extending the period which in turn dropped the monthly repayments. Good Luck!!