This payment amount is independent of the additional costs on a home sometimes handled in escrow, such as property taxes and property insurance. Consequently, payments made by the borrower may change over time with the changing escrow amount, but the payments handling the principal and interest on the loan will remain the same.

Fixed rate mortgages are characterized by their interest rate (including compounding frequency, amount of loan, and term of the mortgage). With these three values, the calculation of the monthly payment can then be done.

Fixed rate mortgages are the most classic form of loan for home and product purchasing in the United States. The most common terms are 15-year and 30-year mortgages, but shorter terms are available, and 40-year and 50-year mortgages are now available (common in areas with high priced housing, where even a 30-year term leaves the mortgage amount out of reach of the average family).

Outside the United States, fixed-rate mortgages are less popular, and in some countries, true fixed-rate mortgages are not available except for shorter-term loans. For example, in Canada the longest term for which a mortgage rate can be fixed is typically no more than ten years, while mortgage maturities are commonly 25 years. In Australia banks are unable to offer fixed rates for terms longer than 15 years due to funding constraints.

In finance, negative amortization, also known as Neg Am, occurs whenever the loan payment for any period is less than the interest charged over that period so that the outstanding balance of the loan increases. As an amortization method the shorted amount (difference between interest and repayment) is then added to the total amount owed to the lender. Such a practice would have to be agreed upon before shorting the payment so as to avoid default on payment.

The fact that a fixed rate mortgage has a higher starting interest rate does not indicate that this is a worse form of borrowing compared to the adjustable rate mortgages. If interest rates rise, the ARM cost will be higher while the FRM will remain the same. In effect, the lender has agreed to take the interest rate risk on a fixed rate loan.

Some studies have shown that the majority of borrowers with adjustable rate mortgages save money in the long term, but that some borrowers pay more. The price of potentially saving money, in other words, is balanced by the risk of potentially higher costs. In each case, a choice would need to be made based upon the loan term, the current interest rate, and the likelihood that the rate will increase or decrease during the life of the loan.

The risk resulting from the fact that interest or dividends earned from an investment may not be able to be reinvested in such a way that they earn the same rate of return as the invested funds that generated them. For example, falling interest rates may prevent bond coupon payments from earning the same rate of return as the original bond.Pension funds are also subject to reinvestment risk especially with the shorterm nature of cash investments there is always the risk that future proceeds will have to be reinvested at a lower interest rate.

In the case of a mortgage-backed security (MBS), prepayment is perceived as a risk, because mortgage debts are often paid off early in order to incur lower total interest payments through cheaper refinancing. The new financing may be cheaper because the borrower's credit rating has improved or because interest rates are lower, but in either case, the payments that would have been made to the MBS investor would be above market rates.

Redeeming such loans early through prepayment reduces the upside of credit & interest rate variance in an MBS. The downside of these variances (interest rates rises or creditworthiness declines) does not normally induce a refinancing (since the fixed mortgage payments are now at below-market rates). The fact that MBS-holders are exposed to downside prepayment risk, but rarely benefit from it, means that these bonds must pay a slightly higher interest rate than similar bonds without prepayment risk, to be attractive investments.