9. A party to a construction contract shall, not later than 5 days after the date on which any payment–
(a)becomes due from him; or
(b)would have become due, if–
(i)the other party had carried out his obligations under the contract; and
(ii)no set-off or abatement was permitted by reference to any sum claimed to be due under one or more other contracts,
give notice to the other party to the contract specifying the amount (if any) of the payment he has made or proposes to make, specifying to what the payment relates and the basis on which that amount is calculated.