FIDIC

Interim Payment Under FIDIC — Certification, Notice, and Cash Flow

The interim payment mechanism is the contractor’s lifeline for project financing. Understanding the payment procedure, the engineer’s duties, and the contractor’s rights to payment protection is fundamental to effective cash flow management on FIDIC projects.

6 min read · Updated 23/05/2026

In this article

1. The FIDIC Interim Payment Mechanism
2. Payment Application and Valuation
3. The Engineer’s Certificate
4. Payment Notice and Due Date
5. Withholding and Disputes
6. Statutory Payment Rights

Key takeaway

FIDIC interim payments flow through the engineer’s certificate to the employer’s payment obligation. The engineer’s certificate is not a final determination but a certification of work done and cost due. Payment notices, due dates, and the contractor’s suspension right are contractually specified and must be strictly observed.

1. The FIDIC Interim Payment Mechanism

FIDIC Red Book 2017, Clause 14 sets out the interim payment process. The contractor submits a monthly statement (by the 25th day of each month, or as specified in the tender schedule) detailing: work executed and its value; materials on site; retention held; and the sum due for the month.

The engineer then certifies the amount due. This certification is not optional — Clause 14.3 states that the engineer “shall” issue the certificate, confirming the amount that the engineer considers is fairly due to the contractor. The engineer is required to act fairly and independently in making this assessment.

The employer then pays the certified amount by the due date (typically 28 days from the date of the certificate, or as specified in the special conditions). The due date for payment is a binding contractual deadline — not a guide.

Retention (typically 5–10% of each certificate) is held by the employer as security and released in tranches: usually 50% on practical completion and 50% at the end of the defects liability period.

2. Payment Application and Valuation

The contractor’s monthly statement must be detailed and accurate. It should show:

• Description of works completed with reference to the drawings and bills of quantities
• Quantity of work executed (linear metres, square metres, tonnes, number of units)
• Rate applied and cost for each item
• Variations executed (with engineer’s approval)
• Materials on site (with evidence of ownership and proof of payment)
• Retention percentage deducted
• Previous certifications and cumulative total
• The net sum due

The statement should be submitted with supporting documentation: measurement sheets certified by the contractor’s site representative and the engineer’s site supervisor; invoices for materials on site; proof of payment to suppliers; photographic evidence of work executed; and any other evidence the engineer may reasonably require.

The engineer is obliged to examine the statement and to either certify the amount claimed or notify the contractor of the reasons for any reduction. Silence does not constitute certification — the engineer must actively issue a certificate.

3. The Engineer’s Certificate

The engineer’s certificate is the formal document authorising the employer to pay. It states: the amount the engineer considers is fairly due; the retention deducted; the net sum payable; and the date by which payment is due.

The certificate is not a final determination of the contractor’s entitlement. It is an interim certification based on the engineer’s assessment of work done and value earned at that point. It can be adjusted in subsequent certificates or in the final account if further information becomes available.

However, the certificate is binding on the employer for the purposes of that month’s payment. The employer cannot refuse to pay on the basis of a different assessment — the employer must pay in accordance with the engineer’s certificate, or if payment is disputed, the contractor has rights under the contract to suspend work and pursue the certified amount through the dispute resolution mechanism.

4. Payment Notice and Due Date

The payment obligation is triggered on the date of the engineer’s certificate. The due date for payment is specified in the contract — typically 28 days after the certificate, or 14 days after receipt of the contractor’s statement (whichever is later).

The due date is a contractual deadline. The employer is obliged to pay by that date. If the employer does not pay by the due date, the contractor has contractual rights: to suspend work (with notice), to charge interest on late payment, and potentially to claim damages for non-payment.

Under FIDIC Red Book 2017, Clause 14.8, if payment is not made within 7 days of the due date, the employer is in breach of contract, and Clause 16.2 allows the contractor to terminate the contract if the employer remains in breach after a 28-day notice.

5. Withholding and Disputes

The employer can withhold payment only where the contract expressly permits it. FIDIC Red Book allows withholding for: the contractor’s failure to comply with insurance obligations (Clause 18); non-compliance with the programme or other obligations; and defects liability. The basis for withholding must be clearly stated, and the employer must provide notice to the contractor of the withholding and its reason.

A general dispute about the contractor’s claim does not justify withholding the certified amount. If the employer disputes the engineer’s certification, the employer must pay the certified amount and pursue the dispute through the contract’s dispute resolution mechanism (engineer’s determination or arbitration).

Disputes about payment are typically resolved through adjudication or expedited arbitration, which are faster than full arbitration. Under many FIDIC contracts, a provisional decision is made within days, allowing the contractor to access the certified amount whilst the underlying dispute is resolved.

6. Statutory Payment Rights

In jurisdictions where the Housing Grants, Construction and Regeneration Act 1996 (or equivalent legislation) applies, contractors have statutory payment rights that cannot be excluded. These include: the right to a payment notice identifying the sum due; the right to receive payment by the due date; and the right to suspend work for non-payment.

Even where FIDIC is the governing law, some jurisdictions (the UK, Singapore, and others) have statutory payment regimes that override private contract terms. The contractor should understand the statutory rights in the project’s governing law jurisdiction and assert them where the contract provides less protection.

Under FIDIC Red Book, the contractual payment mechanism typically aligns with statutory requirements — FIDIC provides for a certificate, a due date, and a suspension right — all of which are recognised in most statutory payment regimes. However, the contractor should verify this in advance of executing the contract.

Payment Issues on FIDIC Projects?

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