Commercial & Contract · Mandatory · Construction

Interim Payment Application

A monthly application for payment for work completed to date.

Last reviewed: 29 March 2026 — This guide reflects UK law as of this date. Construction Act 1996 / JCT remains current with no amendments enacted as of 29 March 2026. Next scheduled review: 29 March 2027.

Legal basis	Housing Grants, Construction and Regeneration Act 1996 s.109 (as amended 2009) + JCT Standard Building Contract / Intermediate Building Contract
Statutory right	Every party to a construction contract has a statutory right to interim payments under s.109 of the Construction Act 1996 — this right cannot be contracted out of
Payment cycle	Contractor submits application → employer issues payment notice within 5 days of due date → employer may issue pay-less notice not less than 5 days before final date for payment → payment by final date
Smash and grab	If the employer fails to issue a valid payment notice or pay-less notice in time, the contractor's application becomes the notified sum — the full amount applied for must be paid (smash and grab adjudication)

1. Interim Payments — The Cash Flow Lifeline

Interim payment applications are the mechanism by which contractors receive payment for work carried out during each payment period. Cash flow is the lifeline of every construction project — without regular interim payments, contractors cannot pay subcontractors, suppliers cannot be paid for materials, and the supply chain collapses. The Construction Act 1996 recognises this by providing a statutory right to interim payments for every party to a construction contract.

The interim payment application is not merely a request for money — it is a document that triggers a series of statutory obligations on the employer. Once a valid application is submitted, the employer must issue a payment notice within 5 days of the payment due date, stating the sum considered due and the basis on which it has been calculated. If the employer intends to pay less than the notified sum, a pay-less notice must be served not less than 5 days before the final date for payment. If the employer fails to serve either notice in time, the contractor's application becomes the notified sum and the full amount must be paid by the final date for payment.

This mechanism — commonly referred to as "smash and grab" adjudication — was established to protect contractors from employers who delay or avoid engaging with payment applications. The courts have consistently enforced the principle that an employer who misses the payment notice deadline must pay the full applied sum, regardless of whether the sum is considered to be a genuine reflection of the work done. The employer's remedy is to commence a true value adjudication after paying the notified sum.

If the employer misses the payment notice deadline, the contractor's application becomes the notified sum

This is one of the most powerful provisions in UK construction law. Under s.110A of the Construction Act 1996, where the employer fails to issue a payment notice within 5 days of the payment due date, the contractor's payment application is treated as the payment notice — and the sum stated in the application becomes the notified sum that must be paid by the final date for payment. The employer cannot subsequently issue a late payment notice to reduce the amount. The only option is to serve a valid pay-less notice (if still within time) or to pay the full sum and then commence a true value adjudication.

2. Interim Payment Application — Content

Field	Detail
Application number	Sequential number for each interim application (e.g. IPA-001, IPA-002). Provides a clear audit trail from first application through to final account.
Date	The date of the application. Must align with the contractual payment due dates specified in the contract particulars.
To	Full legal name and address of the employer or contract administrator to whom the application is submitted.
Project reference	Project name, site address, and contract reference number. Ensures the application is linked to the correct contract.
Cumulative gross value	The total gross value of all work properly executed from commencement to the date of the application. Measured against the contract sum, bill of quantities, or schedule of rates.
Previous certified amount	The total amount previously certified (or applied for and paid) up to the previous interim period. Deducted from the cumulative gross value to calculate the current period's value.
Gross value this period	Cumulative gross value less previous certified amount. This is the value of work carried out during the current interim period.
Retention	The retention percentage applied to the gross value (typically 3–5%). Half released at practical completion; balance at end of defects liability period.
Daywork	Value of any daywork carried out during the period, supported by signed daywork sheets. Daywork is work instructed on a cost-plus basis outside the measured works.
Materials on site	Value of materials delivered to site but not yet incorporated into the works. Must be properly stored, protected, and identifiable. Some contracts also allow for materials off-site (stored at supplier premises).
Net sum due	The total amount claimed after deduction of retention and addition of daywork and materials on site. This is the sum the contractor is applying for in this interim period.
VAT	VAT at the prevailing rate applied to the net sum due. The VAT amount and the gross total including VAT must be clearly stated.
Signed by	Name, position, and signature of the authorised person submitting the application on behalf of the contractor. Only authorised representatives should submit payment applications.

3. Common Mistakes

Submitting the application late

The contract specifies payment due dates and the timing for submission of interim applications. A late application may not trigger the employer's obligation to issue a payment notice within the statutory timeframe, weakening the contractor's position. Late applications also disrupt the payment cycle for the entire supply chain — subcontractors and suppliers downstream depend on the contractor being paid on time. Applications should be submitted on the contractual due date, every period, without exception.

No supporting measurement or breakdown

An interim payment application without supporting measurement, valuation breakdown, or evidence of work done is difficult for the contract administrator to assess and easy for the employer to challenge. Every application should include a detailed breakdown of the cumulative value claimed, cross-referenced to the bill of quantities or schedule of rates, supported by measurement records, progress photographs, and signed daywork sheets where applicable. A well-supported application is processed faster and is far less likely to be subject to significant abatement.

4. Frequently Asked Questions

What is the difference between the due date and the final date for payment?▾

The due date is the date on which the payment obligation arises — it is the date from which the employer's 5-day window to issue a payment notice begins. Under JCT contracts, the due date is typically the date of the interim valuation or the date specified in the contract particulars. The final date for payment is the last date by which the employer must actually make payment. Under JCT, the final date for payment is typically 14 days after the due date (though the contract particulars may specify a different period). If the employer fails to pay by the final date for payment, the contractor has the right to suspend performance under s.112 of the Construction Act 1996, provided the contractor gives at least 7 days' written notice of intention to suspend.

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