If the Authority makes an overpayment to the Contractor it is more convenient and secure for it to be able to recover that amount by setting it off against the monthly payment to the Contractor, rather than having to recover it separately. The Contract should be clear as to whether such set off is allowed by either or both the parties.
The WIDP Contract (Clause 46) allows the Authority to set off any amount owed to it by the Contractor against the Monthly Payment, or any other amounts due to the Contractor. There is no reciprocal right for the Contractor.
The Contract Manager should ensure that the section of the Contract Management Manual that sets out procedures in relation to payment of invoices highlights the right of set off.