Tide always identifies the life-cycle position of every Risk reported, whether through a Risk or Premium Bordereau. If it is identified as a New or Renewal Risk, then Tide knows that it is the first reporting of the Risk, and therefore the Gross Premium value must be positive (negative Gross Premium can only be received in an Endorsement, Cancellation, or Reinstatement). Tide runs the 'Validate initial premium is positive' Validation Rule to check this. 

If Tide identifies a negative Gross Premium in the first reporting of a Risk, then Tide will raise the 'First reporting of risk with negative premium' error. You will then have the option to change the Gross Premium value, in the instances that this is a valid negative premium in the first reporting then you are able to select Continue.