This study proposes a frequency estimation technique for single-phase systems in the presence of harmonic pollution. The technique is based on three consecutive samples and has an infinite-impulse response, thus being a relatively simple one. It is immune to harmonic distortion at both nominal and off-nominal frequencies. In addition, it offers frequency step estimation with a settling time of one nominal fundamental cycle. Compared to the competing algorithm based on three consecutive samples, the proposed one offers a faster dynamic response and improved estimation at steady state, and is also computationally efficient, thus requiring less hardware and cost for implementation. Simulated and real-time experimental results confirm that the proposed technique exhibits superior performance when compared to the considered similar algorithm.