lifetime cap; the negative amortization cap; and others. Many lenders created their own software programs, and World Savings even had contracted special calculators to be made by Calculated Industries specifically for their “pick a payment” program. However, by the late 2000s the Great Recession brought an end to many of the creative “pick-a-payment” type of loans which left many borrowers with higher loan balances over time, and owing more than their houses were worth. This also helped reduce the more complicated calculations that went along with these mortgages. Total interest paid formula The total amount of interest that will be paid over the lifetime of the loan is the difference of the total payment amount () and the loan principal (): where is the fixed monthly payment, is the number of payments that will be made, and is the initial principal balance on the loan. The cumulative interest paid at the end of any period N can be calculated by: Outside the U.S. In the United Kingdom, the FCA - Financial Conduct Authority (formerly the FSA - Financial Services Authority) regulates loans secured on residential property. It does not prescribe any specific calculation method. However, it does prescribe that, for comparative purposes, lenders must display an Annual Percentage Rate as prominently as they display other rates. In Spain, the regulatory authority (Banco de España) has issued and enforced some good practices, such as clearly advertising the Annual Percentage Rate and stating how and when payments change in variable rate mortgages. See also Bridge financing Financing Fixed rate mortgage Adjustable-rate mortgage Mortgage loan Promissory note Loan origination Subprime lending References External links Mortgage Calculator at NYTimes.com Accounting software Mortgage