Each state in US has different usury laws regarding interest rates. For example, in Texas, the legal rate of interest is 6%. Interest can be charged only 30 days after an account was due. The judgment rate of interest is 18% or the rate in the contract, whichever is less. There are a number of specific ceilings for different types of loans like car loans, home loans, please see counsel for information.
However, banks have separate rules for interest rates. Due to the high inflation about three decades ago, in 1980, the federal government passed a special law which allowed national banks (the banks that have the word “national” or the term “N.A.” in their name, and savings banks that are federally chartered) to ignore state usury limits and pegged the rate of interest the banks could charge at a certain number of points above the federal reserve discount rate.
Additionally, specially chartered organizations like small loan companies and installment plan sellers (like car financing companies) have their own rules regarding the interest rate they can charge.