An interest rate swap in which the floating rate is set in arrears. This means, the floating rate is determined based on the value or level of a specific reference rate at the end of the reset period. Once defined, the rate is applied backwardly or retroactively to that period. However, the fixed rate is set at or relative to a market rate.

The swap in-arrears has several other names including: in-arrears swap, delayed reset swap, reset swap, LIBOR in-arrears swap, back-set swap, arrears swap, and back end set swap.