What is the notified sum? The one number the Construction Act says must be paid, and how it comes to be yours

Published 24 September 2026 · Updated 10 October 2026 · VariationFlow

A plain-English guide to the notified sum under the Construction Act for UK subcontractors: how the sum is fixed by the payer’s payment notice, how the payee’s own application takes its place when the payer says nothing, what a pay less notice can and cannot do to it, why retention comes off before it and not after, and what “pay now, argue later” means in practice.

You applied for £58,000. The main contractor sent nothing within five days of the due date, nothing before the pay less deadline, and £44,000 on the final date with a spreadsheet attached explaining the difference. The spreadsheet may be right about every line. It still has nothing to do with what was due on that day, because the Act had already fixed the number, and the number was £58,000.

That number is the notified sum. It is the hinge of the whole payment regime, the thing a smash-and-grab adjudication enforces and the thing a pay less notice exists to reduce, and most people on both sides of a sub-contract could not say how it comes to exist.

The idea in one sentence

For every payment cycle the Construction Act requires somebody to state, in a notice, the sum they say is due and the basis of it, and whatever sum is stated in the notice that counts becomes the notified sum, which section 111 says the payer must pay on or before the final date for payment unless it serves a pay less notice in time. Everything else is detail about which notice counts.

How the sum gets notified

• The payer’s notice. Section 110A requires the contract to provide for a payment notice not later than five days after the due date, stating the sum the payer considers due and the basis on which it is calculated. Most contracts put that notice on the payer. Where it is served in time, the sum in it is the notified sum, even where that sum is nil.
• The payee’s application, where the contract allows for one. Section 110B(4) says that where the contract allows or requires the payee to give a notice before the payer’s notice is due, the ordinary interim application, and the payer then gives no notice, the payee’s application stands as the payment notice. So on a JCT or NEC sub-contract with a proper application in, silence from the payer makes your application the notified sum, and nothing is postponed, because your notice went in before the payer’s was due.
• The payee’s default notice, where there was no application. Where the contract makes no provision for a payee application and the payer gives no notice, section 110B lets the payee serve its own payment notice after the payer’s was due. Section 110B(3) then postpones the final date for payment by the number of days the default notice was late, and the pay less deadline, counted back from the final date, moves with it.

The second route is the one that matters on most sub-contracts, and it is why the application has to be a proper one: given in time, for a stated sum, showing the basis on which it was calculated, and in the form the contract asks for. An application that fails on any of those is not a notice under section 110B(4), and there is then no notified sum to enforce.

What a pay less notice does to it

Section 111 lets the payer pay less than the notified sum only by serving a pay less notice no later than the prescribed period before the final date for payment, seven days under the Scheme where the contract is silent, stating the sum the payer now considers due and the basis of that sum. A notice in time and in that form replaces the notified sum with the pay less figure. A notice that is late, or names a sum with no basis, does not, and on the current authorities is a nullity. The notified sum then stands and is payable in full on the final date.

Two limits on that. The notified sum is the sum due, so retention comes off before it, not after: retention is a contractual deduction taken in arriving at the sum due, at the rate you agreed, and it is not a pay less deduction. A smash-and-grab recovers the net figure. And the sum that is payable is the unpaid balance of it. If £44,000 of the £58,000 has been paid, what is overdue on the final date is £14,000, not £58,000.

Pay now, argue later

The Court of Appeal in S&T v Grove settled the sequence. The payer pays the notified sum, and may then start its own adjudication on the true value of the work. It may not do the second without doing the first. So the spreadsheet attached to the short payment is not worthless; it is the payer’s case for a true-value adjudication it can only bring once it has paid. Until then the notified sum is a debt, with interest running on it, and it is enforceable through an adjudication that turns on dates rather than on valuation.

The dates the sum hangs on

Every one of the notices above is timed from the due date, so the notified sum only exists against a calendar. On the Scheme the due date is the later of seven days after the end of the period and the making of the claim, the payer’s notice is due five days after it, the final date is seventeen days after it, and the pay less notice is due seven days before the final date. On the JCT Design and Build main contract, read from a licensed copy, the due date is seven days after the Interim Valuation Date, the payment notice is due five days later, the final date is fourteen days from the due date and the pay less notice is due five days before it; your sub-contract sets its own periods and they are not the main contract’s. On the NEC4 Engineering and Construction Subcontract with Option Y(UK)2, the due date is fourteen days after the assessment date. Whatever the form, the five days for the payer’s notice are the Act’s and do not move, and all of it is reckoned under section 116, which leaves out only Christmas Day, Good Friday and bank holidays.

Where subcontractors lose it

• The application that was not a notice: late, or without a stated sum and basis, or not in the contract’s form, so that silence from the payer produced nothing.
• The dates nobody counted, so that a late pay less notice was treated as a good one and the short payment was accepted as a valuation dispute.
• The short payment that went “into the final account”, where a sum the Act said was due on a named day became one more disputed line and settled at half.

How VariationFlow keeps it

The payment timeline diarises each cycle’s due date, payer’s notice date, pay less deadline and final date from the contract profile, and the notified-sum tracker on each cycle works out whether a notified sum exists yet, whether the payer’s notice re-based it, whether a pay less notice was served and in time, and what unpaid balance is payable once the window closes, net of retention. A pay less notice that appears out of time is flagged for checking rather than asserted, because the difference between the two is the difference between a claim and a mistake.

This guide is general information rather than legal advice. Whether a particular application or notice was good turns on your own contract’s words and dates, and a short payment of any size is worth counting with an adviser before the final date passes.