P.R. Laws tit. 31, § 4591
In the absence of a prior agreement in writing, the rate of interest upon the loan or forbearance of money or goods, or on any type of obligation or agreement, shall be at a rate of six (6) dollars annually on each one hundred (100) dollars or upon its equivalent value, and at the same rate for a greater or lesser sum, or for a longer or shorter period; Provided, however, That no rate of interest shall be fixed in excess of nine (9) dollars a year on each one hundred (100) dollars or upon its equivalent in value, when the capital sum subject to the loan or agreement does not exceed $ 3,000, and of eight (8) dollars a year on each one hundred (100) dollars, when it exceeds said amount. It shall be lawful to discount bills and notes and other similar obligations within the limits defined herein.
History —Civil Code, 1930, § 1649; Aug. 17, 1933, No. 5, p. 26; July 9, 1985, No. 100, p. 332.