In the United States, the maximum cost of borrowing for consumer loans is regulated by the Federal Reserve Board, through the Truth in Lending Act (TILA). The maximum cost of borrowing is known as the Annual Percentage Rate (APR) and it is the total cost of borrowing, including interest and any additional fees, expressed as a percentage of the loan amount.

The maximum APR for most types of consumer loans in the United States is not capped but it should be disclosed and accurate. This includes loans such as personal loans, credit cards, and lines of credit. However, some states have set their own caps on the APR, which may be lower than the federal cap.

However, the costs of borrowing can be hidden in various ways. One way is through the use of compounding interest, which can make the total cost of borrowing much higher than the stated interest rate. Additionally, some lenders may charge fees or penalties that are not included in the APR, such as late payment fees, balance transfer fees, or prepayment penalties. These fees can significantly increase the total cost of borrowing, making it difficult for consumers to compare the true cost of loans.

To avoid hidden costs, it is important for consumers to carefully read and understand the terms and conditions of any loan they are considering, including the APR, and any additional fees or penalties. It is also important to compare the rates and terms of different lenders to ensure you get the best deal.