When does discharge become effective under the FIDIC Red Book (edition 1999)?

Under the FIDIC Red Book 1999, discharge becomes effective when the Contractor has received full payment certified by the Final Payment Certificate and the return of the Performance Security (Sub-Clause 14.10). Both elements must be completed for the contract to be considered fully discharged, releasing the Contractor from further obligations or liabilities under the contract.

Option A is incomplete as payment alone does not fully discharge the Contractor.

Option B is incomplete as return of Performance Security alone is insufficient.

Option D is incorrect because the contract does not require a discharge notice signed by the Employer beyond these conditions.