The date on which the periodic payment terms and conditions of a swap agreement are established. In other words, the rare fixing date refers to the point in time when an underlying interest rate readjusts to account for changes in a designated reference interest rate (such as LIBOR). Typically, it coincides with the payment date or two business days earlier according to applicable market conventions or the pre-agreed terms of a particular agreement.

It is alternatively known as a rollover date, a roll date, or a reset date.