How long does an investigation usually take? July 28, 2021 21:43 This varies depending upon the complexity of the case and how cooperative the parties are. We usually complete an investigation within six months, although it could be much shorter or longer than this. Related articles What if I want to settle my case rather than proceed to court? Who has the burden of proving discrimination? What are the remedies to a discrimination complaint? What if I am discharged? How long does the plan cover?