We develop a theoretical model that generates an optimal Taylor rule in which structural parameters can change in a two monetary policy regime under inAiation targeting. The theoretical model gives rise to an empirical structural STAR model. SpeciA–cation tests suggest a LSTAR speciA–cation of the transition function with the output gap lagged four periods as the transition variable. We A–nd estimate this LSTAR model in reduced form that is used to recover structural deep parameters, like the weights in Banco de la Rep I‡blicaA­s loss function for the two monetary regimes during the period of inAiation targeting from IV.2000 to IV.2017. We A–nd evidence that the nonlinear LSTAR Taylor rule outperforms in terms of within sample predictions the linear optimal Taylor rule which supports the conclusion that under inAiation targeting the behavior of Banco de la Rep I‡blica (Banrep) is described better with a two monetary regime policy than with a single monetary regime. We also A–nd evidence that suggests that the monetary policy has been consistent with the so called Taylor principle in both regimes where in one of these Banrep has reacted aggresively to inAiationary pressures while in the other regime it has reacted strongly, but not aggresively, to recessionary pressures. The asymmetric behavior of the monetary policy can be rationalized through asymmetric neo Keynesian price stickiness.