then compete on details by making analyses of how to use data such as these along with any other data they gather from the application and history with the cardholder, to determine an interest rate that will attract borrowers by remaining competitive with other banks and still assure a profit. Debt-to-income ratio (DTI) is another important factor for determining interest rates. The bank calculates it by adding up the borrower's obligated minimum payments on loans, and dividing by the cardholder's income. If it is more than a set point (such as 20% in this example) then loans to that applicant are considered a higher risk than given by this table. These loss rates already include incomes the lenders receive from payments in collection, either from debt collection efforts after default or from selling the loans to third parties for further collection attempts, at a fraction of the amount owed. To use the chart to make a loan, determine an expected rate of return on the investment (X) and add that to the expected loss rate from the chart. The sum is an approximation of the interest rate that should be contracted with the borrower in order to achieve the expected rate of return. Interrelated fees Banks make many other fees that interrelate with interest charges in complex ways (since they make a profit from the whole combination), including transactions fees paid by merchants and cardholders, and penalty fees, such as for borrowing over the established credit limit, or for failing to make a minimum payment on time. Banks vary widely in the proportion of credit card account income that comes from interest (depending upon their marketing mix). In a typical UK card issuer, between 80% and 90% of cardholder generated income is derived from interest charges. A further 10% is made up from default fees. Laws Usury Many nations limit the amount of interest that can be charged (often called usury laws). Most countries strictly regulate the manner in which interest rates are agreed, calculated, and disclosed. Some countries (especially with Muslim influence) prohibit interest being charged at all (and other methods are used, such as an ownership interest taken by the bank in the cardholder's business profits based upon the purchase amount). United States Credit CARD Act of 2009 This statute covers several aspects of credit card contracts, including the following: Limits over-the-limit fees to cases where the consumer