Over the past few years under deposit corrosion (UDC) has been frequently cited by operators corrosion engineers failure forensic analysts asset integrity authorities and RCA (Root Cause Analysis) specialists as being a major player in different failures within the oil and gas operations. It has also been identified sometimes as a stand alone corrosion mechanism separate from CO2 H2S Microbiological induced corrosion crevice or galvanic corrosion. This paper presents an overview of UDC definitions commonly used laboratory testing methods as they relate to the prevalent UDC mechanism and finally proven mitigation measures. It highlights the applications and limitations of each testing method and sets the framework for the standard and the novel mitigation routes.