The main risk at the end of a project is that a final output will be delivered by the consultant, and payment made, without a proper check that the deliverables specified in the contract have all been provided. An obvious mitigation strategy is therefore to conduct a thorough reconciliation of output received from the consultant against the outputs specified in the contract.
The reconciliation should take place with sufficient time to spare for additional work by the consultant, if required. And don’t forget to include any contract variations in the reconciliation process.