Variable-rate mortgage

A variable-rate mortgage or adjustable-rate mortgage (ARM) is a mortgage loan with the interest rate on the note periodically adjusted based on an index which reflects the cost to the lender of borrowing on the credit markets. The loan may be offered at the lender's standard variable rate/base rate. There may be a direct and legally defined link to the underlying index, but where the lender offers no specific link to the underlying market of index they can choose to increase or decrease at their discretion. The term "variable-rate mortgage" is most common outside the United States, whilst in the United States, "adjustable-rate mortgage" is most common, and implies a mortgage regulated by the Federal government,  with limitations on charges ("caps"). In many countries, adjustable rate mortgages are the norm, and in such places, may simply be referred to as mortgages.

Adjustable rate mortgage is a mortgage that features predetermined adjustments of the loan interest rate at regular intervals based on an established index. The interest rate is adjusted at each interval to a rate equivalent to the index value plus a predetermined spread, or margin, over the index, usually subject to per-interval and to life-of-loan interest rate and/or payment rate caps.