The negative float is a very popular hot topic in the scheduling field and it’s generated when the late dates are less than the early dates and usually it’s accompanied with a delay in the project, and a lot of project management professionals think that the only reason for a negative float is because a constraint that has been used in the schedule. Although the first thing you look for when you see a negative float is the constraints that are applied to the schedule, but that not the only reason that generates the negative float in P6.