What needs to be included in a Payment Notice?

Two things: the sum the payer thinks is due as at the Due Date, the date the payment obligation is fixed, and the workings behind it, shown line by line so the payee can follow the arithmetic. A Payment Notice is the payer's statement of the sum due for the round, and that sum can be lower than the payee applied for, or even zero, but a zero still needs its calculation set out. Serving nothing because the sum is nothing is the costly mistake, because silence lets the payee's application stand as the Notified Sum, the amount that legally must be paid. Head the document a Payment Notice, cite the contract, round and the application it responds to, and date it. The classic content failure is a bare figure with no workings, or deductions asserted without any calculation.

A groundworks subcontractor applies for £35,000 but the surveyor believes almost nothing new was done and only a token amount is earned. He ignores the application because there is nothing to pay, and stays silent. That silence lets the £35,000 stand as the Notified Sum by default. He should have served a Payment Notice, headed as such and citing the round and application, stating say £1,000 as due at the Due Date with a short breakdown, or even zero with the arithmetic shown. A nil notice with its workings protects the payer, whereas the tidy looking silence hands over the full £35,000.