A rate of interest that can be used if the reference rate for a certain arrangement or contract (a facility, instrument, etc,) is unavailable or not published. It is an alternative rate of interest that would have been applicable under the terms of the contract if the defined rate had become unavailable for some reason (such as the case when the reference rate cannot be determined and published).

A fallback rate is a replacement rate that can be used for calculation and determination of financial obligations related to an arrangement or contract (or an instrument or product, e.g., floating rate bonds).

Fallbacks (fallback rates) are meant to provide an alternative way- how issuers, investors and other market participants should go on transacting in the event that a benchmark ceases to exist or is unavailable. For example, fallbacks in transaction documents for floating-rate bonds entail that the calculation agent selects another suitable rate in the event that the quoted floating rate is not available.