FIDIC Clause 14.6: The Interim Payment Certificate Explained
Payment is where contractors lose money silently. Not in a single catastrophic event, but across dozens of payment cycles where the mechanism is working against them in ways that were locked into the contract before the project started. The Contractor signs a FIDIC subcontract, the payment provisions are in Sub-Clauses 14.6 and 14.7, and three months into the project the commercial team realises that the 28-day certification window in the General Conditions was extended to 60 days in the Particular Conditions, and that the 56-day payment period was extended to 90 days on top of that. The result is a 150-day payment cycle on a contract with monthly valuations. That is five months of work financed by the Contractor before a single payment is received.
This guide covers exactly what Sub-Clause 14.6 requires, how Particular Conditions modify the standard position, what happens when the Engineer fails to certify, and how AI identifies these modifications at the point where they can still be negotiated.
What Clause 14.6 Requires
Sub-Clause 14.6 governs the Engineer's obligation to issue an Interim Payment Certificate (IPC). It sits within Clause 14, which covers the full payment mechanism from the Contract Price through to the Final Payment Certificate.
Under the FIDIC Red Book (both 1999 and 2017 editions), the payment process begins with the Contractor submitting a Statement. Under the 1999 edition, this is a monthly Statement setting out the amounts the Contractor considers due, supported by documents showing the basis of calculation. Under the 2017 edition, the same process applies under Sub-Clause 14.3, with updated content requirements.
Once the Engineer receives the Contractor's Statement, Sub-Clause 14.6 requires the Engineer to issue an IPC within 28 days. The IPC must state the amount the Engineer determines to be due, with supporting particulars. If the Engineer determines that an amount different from the Contractor's Statement is due, the IPC must set out the basis for the Engineer's determination.
The IPC is not itself the payment. It is the certification that triggers the Employer's payment obligation under Sub-Clause 14.7. Under the 1999 Red Book, the Employer must pay the certified amount within 56 days of the Contractor's Statement. Under the 2017 edition, the payment obligation runs from the date of the IPC rather than from the Statement, which changes the reference point but not the fundamental structure.
The combined effect of Sub-Clauses 14.6 and 14.7 under the standard 1999 Red Book position is a maximum payment cycle of 56 days from Statement submission. Under the 2017 edition, the cycle from Statement to payment is 28 days (for the IPC) plus 56 days from the IPC, giving a potential cycle of up to 84 days at the outer limit of the standard position.
In practice, the standard position is rarely what applies. Particular Conditions modify both timelines on the majority of bespoke FIDIC contracts.
The 28-Day Engineer Certification Window
The 28-day certification period is the first point at which the payment clock can be extended against the Contractor's interests. Under the standard form, the Engineer has 28 days from receipt of the Contractor's Statement to issue the IPC. This is not a 28-day window to query the Statement. It is a 28-day window within which the Engineer must certify, even if there are items in the Statement that the Engineer disputes.
Where the Engineer disagrees with items in the Contractor's Statement, the correct approach under Sub-Clause 14.6 is to certify the undisputed amount and provide particulars of the basis for any reduction. The IPC is issued for what the Engineer determines is due. The Contractor can then dispute the reduction through the Clause 20 claim procedure, but the undisputed portion should be certified and paid within the standard timelines.
This distinction matters in practice because some Employers and Engineers treat a disputed Statement as a reason to delay certification altogether. Under the standard form, that approach is not permitted. The Engineer's obligation to certify within 28 days is not conditional on the Contractor's Statement being accepted in full. If the entire Statement is disputed, the IPC is issued for zero, or for whatever amount the Engineer determines is due, with full particulars of the basis. The mechanism keeps moving. It does not stop because there is a disagreement.
For QSs managing payment on a live project, the practical consequence is that failure to receive an IPC within 28 days of submitting a Statement is itself a breach of the Engineer's obligation under Sub-Clause 14.6. What the Contractor can do about that breach depends on the specific contract and whether the Particular Conditions have modified the consequences. Under the 2017 edition, the consequences of the Engineer failing to certify are addressed more explicitly than in the 1999 edition.
How Particular Conditions Modify Payment Timing
The 28-day certification period and the 56-day payment period in the General Conditions are the starting point. On most bespoke FIDIC contracts, Particular Conditions modify both.
The most common modifications to Sub-Clause 14.6 are as follows.
Extension of the certification period. The 28-day period is routinely extended to 45 or 60 days in Particular Conditions. On some GCC developer contracts, it is extended to 90 days, bringing the total payment cycle under Sub-Clause 14.7 to 90 days certification plus 56 days payment, which exceeds five months from Statement submission.
Documentation requirements that reset the clock. Some Particular Conditions introduce a requirement that the Contractor's Statement be accompanied by specific supporting documentation, and that the 28-day certification period does not begin until the Engineer has confirmed that the documentation is complete and in the required format. In practice, this provision allows the Engineer to delay the start of the certification window by rejecting documentation on minor technical grounds and requiring resubmission. The commercial effect is an indefinite extension of the certification period under the cover of an administrative requirement.
Withholding provisions for disputed items. Standard Sub-Clause 14.6 requires the Engineer to certify the undisputed amount even where items are in dispute. Particular Conditions sometimes modify this by allowing the Employer or Engineer to withhold certification for the disputed portion pending formal resolution. On a contract with active variations, this provision can result in a significant proportion of each Statement being withheld for months or years while disputes are worked through the resolution process.
Conditions precedent to certification. Some Particular Conditions introduce conditions that must be satisfied before the Engineer can issue an IPC: submission of insurance evidence, confirmation that the programme is current and accepted, or resolution of specific outstanding quality matters. Each condition creates a route by which the Employer can delay certification without it appearing as a direct breach of the payment obligation.
The combined effect of these modifications on the Contractor's cash flow is substantial and direct. A commercial manager reviewing a FIDIC contract at tender stage should calculate the financing cost of the modified payment cycle before pricing the work. On a significant project, the cost of financing a 150-day payment cycle is a material number that belongs in the tender sum if it cannot be negotiated out.
What Happens When the Engineer Fails to Certify
If the Engineer does not issue an IPC within the applicable certification period, whether 28 days under the standard form or a longer period under Particular Conditions, the Contractor has a claim. The nature and strength of that claim depends on the edition and whether the Particular Conditions have addressed the consequences of late certification.
Under the FIDIC 1999 Red Book, Sub-Clause 14.7 provides that the Employer shall pay the amount certified within 56 days of the Contractor's Statement, regardless of when the IPC is actually issued. If the Engineer is late in certifying, the Employer's payment obligation under Sub-Clause 14.7 is not extended by the delay in the IPC. The Employer was required to pay by day 56 from the Statement. If the IPC was not issued and the Employer therefore did not pay, both the Engineer's failure and the Employer's non-payment are breaches of the contract. The Contractor is entitled to financing charges under Sub-Clause 14.8 on any amount not paid by the due date.
Under the FIDIC 2017 Red Book, the payment obligation under Sub-Clause 14.7 runs from the date of the IPC rather than from the Statement. This means that a late IPC does not automatically make the Employer's payment late in the same way. However, the Engineer's obligation to issue the IPC within 28 days is unchanged, and the Contractor's claim for the Engineer's failure to certify is a claim under Sub-Clause 20.2 in the same way as any other breach. The financing charges provision applies to any amount that should have been paid under a timely IPC but was not.
For QSs managing a live project where certification is being delayed, the immediate action is to confirm the contractual position in writing: notify the Engineer of the overdue IPC, state the date on which the Statement was submitted, confirm the certification deadline under the applicable Sub-Clause, and request immediate issuance. This creates a contemporaneous record of the breach and starts the Contractor's claim entitlement under Sub-Clause 20.
The notice requirements for claims arising from late certification are governed by the same Clause 20 conditions precedent that apply to all FIDIC claims. For the full detail on how Clause 20 notice requirements operate and the consequences of missing them, see the guide to FIDIC Clause 20 notice requirements.
How AI Reviews Clause 14.6 Modifications
Manual review of Sub-Clause 14.6 and its Particular Conditions amendments requires reading both the General Conditions and the Particular Conditions simultaneously and tracking every modification. Under time pressure at tender stage, this is one of the first things that gets done quickly rather than carefully.
AI reads the General Conditions and Particular Conditions together, identifies every modification to the standard payment timeline, and quantifies the commercial effect. The output for Sub-Clause 14.6 tells you not just that the certification period has been extended from 28 days to 60 days, but what that extension costs on a contract with monthly valuations and an estimated contract sum: the additional financing exposure per payment cycle.
The modifications that AI identifies in Sub-Clause 14.6 include the period extensions most commonly found in Particular Conditions, but also the less obvious modifications: documentation requirements that reset the certification clock, withholding provisions for disputed items, and conditions precedent to certification that introduce additional ways for the Employer to delay payment without a direct breach.
AI also reviews Sub-Clause 14.7 alongside 14.6 to give a complete picture of the payment cycle: the combined effect of the certification period and the payment period, and any modifications that affect the relationship between them. On the 2017 Red Book, where the Sub-Clause 14.7 payment period runs from the IPC rather than from the Statement, the interaction between the two provisions is particularly important to understand in the context of any Particular Conditions modifications.
For the full process of how AI handles FIDIC contract review from initial upload to risk report, including the payment mechanism, variation rights, and claims procedure, the complete guide to AI construction contract review covers each step in detail.
Frequently Asked Questions
What does FIDIC Sub-Clause 14.6 require the Engineer to do?
Sub-Clause 14.6 requires the Engineer to issue an Interim Payment Certificate within 28 days of receiving the Contractor's Statement. The IPC must state the amount the Engineer determines to be due and, if the Engineer's determination differs from the Contractor's Statement, the basis for the difference. The Engineer's obligation to certify within 28 days is not conditional on the Statement being agreed: if items are disputed, the Engineer certifies the undisputed amount and issues an IPC for that sum, with particulars of the reduction. The IPC then triggers the Employer's payment obligation under Sub-Clause 14.7.
What is the standard payment timeline under FIDIC and how is it typically modified?
Under the 1999 Red Book, the standard position is: Contractor submits Statement, Engineer issues IPC within 28 days, Employer pays within 56 days of the Statement. The total cycle is up to 56 days in the standard form. Under the 2017 edition, the Employer pays within 56 days of the IPC rather than the Statement, giving a potential cycle of up to 84 days. In practice, Particular Conditions routinely extend the certification period to 45 or 60 days and the payment period to 90 days, resulting in total cycles of 120 to 150 days on bespoke FIDIC contracts. The financing cost of that extended cycle is a real commercial number that should be calculated and either priced into the tender or negotiated out before signing.
What happens if the Engineer does not issue an IPC on time?
Under the 1999 Red Book, the Employer's payment obligation under Sub-Clause 14.7 runs from the date of the Contractor's Statement, not from the date of the IPC. A late IPC does not extend the Employer's payment deadline: if the IPC is not issued and the Employer therefore does not pay by day 56 from the Statement, both the late certification and the non-payment are breaches. The Contractor is entitled to financing charges under Sub-Clause 14.8 on unpaid amounts from the due date. Under the 2017 edition, the payment obligation runs from the IPC, so a late IPC delays the payment deadline, but the Engineer's failure to certify on time is still a breach and the Contractor has a claim under Sub-Clause 20.2.
Can the Employer withhold payment if the IPC has been issued?
Once the Engineer has issued an IPC, the Employer's obligation to pay the certified amount by the Sub-Clause 14.7 deadline is clear. The Employer can issue a Pay Less Notice if they dispute the certified amount, but this must be given within the notice period specified in the contract. Under the standard form, the Employer cannot simply withhold payment because they disagree with the IPC: the proper route is to dispute the IPC through the Clause 20 procedure while still paying the certified amount by the due date. Particular Conditions sometimes modify this by allowing withholding for disputed items or pending resolution of outstanding matters, which is why reviewing the payment provisions before signing is essential.
How does the payment mechanism differ between FIDIC 1999 and FIDIC 2017?
The core structure of Sub-Clause 14.6 is similar in both editions: the Engineer must certify within 28 days of the Contractor's Statement. The most significant payment-related change in the 2017 edition is that Sub-Clause 14.7 runs the Employer's payment period from the date of the IPC rather than from the date of the Statement. This changes the practical effect of a late IPC: under the 1999 edition, the Employer's deadline does not move just because the IPC is late; under the 2017 edition, a delayed IPC pushes back the Employer's payment obligation. The 2017 edition also introduced more explicit provisions around the Engineer's role in the payment process and the consequences of certification failure, reflecting lessons from disputes under the 1999 suite. Knowing which edition applies is the first step in any FIDIC payment clause review.
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