There are fixed certificates issued by banks for 30-90 days and some for longer periods. The best rate available now is 14%. After a million pesos you might get a little higher, but not much more. I use COTISA at Banco BHD on Avenida 27 de Febrero. Bancredito has a portfolio of certificates at the same rate. There are companies like Popular Leasing, HizzPizza, Moya Construction(The people who are building Ciudad Satelite),Hache and Mercasid to mention a few that issue offers thru the banks' Bolsa de Valores representatives. Your interest income can be transfered monthly to your bank account, credit card or payable by check.