NEC ECC: At what point does the PM assess cost of correcting Defects under Clause 45.2

If the Employer chooses not to grant the Contractor access after Completion has been certified to correct a Defect as per clause 45.2, when should the Project Manager assess the cost to the Contractor of correcting the Defect?

Should the PM assess the cost immediately and deduct the amount from the next payment assessment or should he wait until the Defects Certificate has been issued to deduct the money?

Option X16 has not been used so there is no Retention.

As the ‘breach’ by the Employer has happened and as there are assessment dates up to the defects date, my opinion would be that the Employer should assess the cost more immediately.

Applying a common sense perspective, If there is then any difference of opinion over this assessment, then it can be ironed out by discussion by the final assessment date immediately after the Defects Certificate is issued. Ideally, this discussion happens before so the PM does not make a guess at what the Contractor’s costs without involving them…