We are the project manager on an NEC3 Engineering and Construction Contract (ECC) Option C (target contract with activity schedule). The contractor has been keeping equipment records on site, which we have had access to, and we have verified the original equipment allocation records when carrying out an audit of the allocation sheets provided. We advised the contractor that these records were not included within the equipment records but were included within its application for payment, and we have disallowed these costs in our payment assessment. Later, the contractor submitted additional costs for equipment that it said had been missed from the application, these costs are for the past 3 years. They have now submitted further additional plant records on a revised equipment allocation sheet. Our question is, under the contract is there a time limit for the contractor to retrospectively submit plant allocation records that are very different from the original plant allocation records? Can we then disallow costs for plant from 3 years ago that can now no longer be verified? And is there any protection for the client due to the contractor’s poor commercial management?