Procurement & finance
Payment Application (Interim Payment Certificate)
The contractor’s periodic claim for payment — measured work, materials on site, variations, less retention and previous payments. The employer’s certificate in response is what actually creates the payment obligation.
The application is an assertion; the certificate is the decision. They are different documents doing different jobs, and conflating them is how contractors come to believe they are owed money that has never been certified.
And the clock matters more than the arithmetic. Most contracts set a period within which the employer must certify and pay, and a period within which any deduction must be notified. Miss the notification window and the deduction can be lost — which is the mechanism a pay-less notice exists to preserve.