1Under a modified AS2124 cost-plus contract requiring fortnightly claims 'for the Cost of the Works that are reasonably, properly and demonstrably incurred', each interim certificate involves a valuation of the whole of the work to date. The superintendent may therefore retrospectively reduce previously certified or paid amounts, here to excise perceived profit components from Schedule C supervision rates. Deletion of cl 42.2 (correction of certificates) is neutral to this conclusion.
2Where the contract requires a certifier to deal with an item mechanically, the certifier acts outside the contract if it reduces that item. Here the principal agreed that the prior payment claims were due and payable and waived any right to amend, audit, dispute or offset them. The superintendent cannot do what the principal itself is contractually barred from doing.
3The common law doctrine of severance may apply to an interim contractual payment certificate unless the contract expressly or impliedly excludes it. An impermissible, specifically identifiable part of the certificate may be blue-pencilled, provided it does not infect the remaining opinion and severance does not substantially alter the certificate's purpose and effect. The existence of final certification and dispute resolution mechanisms does not exclude severance.
