What is due on this certificate?
Enter every figure cumulative to date, as on the subcontract valuation. The defaults reproduce the worked example from the guide.
| Line | Amount |
|---|---|
| Work measured to date | SAR 1,200,000 |
| Approved variations to date | SAR 80,000 |
| Gross valuation | SAR 1,280,000 |
| Less retention at 5% | − SAR 64,000 |
| Less advance payment recovery | − SAR 50,000 |
| Less amounts previously certified | − SAR 900,000 |
| Net amount due this period, before VAT | SAR 266,000 |
The gross valuation to date is SAR 1,280,000. Retention at 5% holds back SAR 64,000. SAR 50,000 of the advance payment is recovered. After SAR 900,000 certified before, the net amount due this period is SAR 266,000 before VAT.
FOR ILLUSTRATION. THE SUBCONTRACT TERMS DECIDE THE REAL FIGURES. NOTHING IS SAVED OR SENT.
How is the net amount of an IPC calculated?
An interim certificate is cumulative. It values everything done to date, takes the deductions to date, and then subtracts the net amount certified on all earlier certificates, so only the difference is paid this period. The table shows each line with the figures from the worked example in the guide to subcontractor payment certificates.
| Line | How it is calculated | Worked example |
|---|---|---|
| Gross valuation | Work measured to date + approved variations to date + materials on site | SAR 1,280,000 |
| Retention | Retention rate × gross valuation, limited to the cap × subcontract value when the subcontract sets a cap | − SAR 64,000 |
| Advance payment recovery | A fixed amount, or a rate × gross valuation, never more than the advance balance | − SAR 50,000 |
| Other deductions | Notified contra-charges and other deductions to date | SAR 0 |
| Previously certified | The net amount certified on all earlier certificates | − SAR 900,000 |
| Net before VAT | Gross valuation − retention − advance recovery − other deductions − previously certified | SAR 266,000 |
| VAT | VAT rate × net before VAT | SAR 0 (no VAT in the example) |
| Net with VAT | Net before VAT + VAT | SAR 266,000 |
Because every line is to date, a retention or recovery that grows with the work is picked up automatically: the increase this period is the difference between this certificate and the last one, and the last one is already inside the amount previously certified.
How do the retention cap and the advance recovery limit work?
Many subcontracts stop deducting retention once it reaches a set share of the subcontract value, for example 5%. Enter that share as the retention cap together with the subcontract value, and the calculator holds back the lower of the retention rate on the gross valuation and the cap.
Advance payment recovery is set as a fixed amount or as a percentage of the gross valuation, and it can never recover more than the advance that was paid. Enter the advance balance and the calculator stops the recovery there. When either limit applies, the certificate line says so.
Should VAT be added to a payment certificate?
Where the subcontractor is registered for VAT and the work is taxable, VAT is charged on the net amount of the certificate, not on the gross valuation. The presets use the standard rates: 14% in Egypt, 15% in Saudi Arabia and 5% in the UAE. Some construction work is taxed at a different rate or not at all, so confirm the rate for your contract with your tax adviser.
Can an AI agent use this calculator?
Yes. In browsers that support WebMCP, a proposed web standard that lets a page offer tools to an AI agent, this page registers one tool, calculate_payment_certificate. An agent passes the same figures as the form and gets back every line of the certificate, the explanation and the result as JSON. The tool only calculates: it runs in the page, saves nothing and sends nothing.
It is the same principle Crolle is built on as an agentic ERP: the agent works through governed tools rather than guessing at screens. In Crolle, the agent is designed to prepare a draft certificate from the project's own records, and an authorised person approves it.
Common questions
What is an interim payment certificate (IPC)?
An interim payment certificate is the document a main contractor issues during a subcontract to state what the subcontractor is owed for the latest period. It values the work done to date, deducts retention, advance payment recovery and other agreed deductions, and subtracts what was certified before. The final certificate settles the whole account after completion.
Is retention worked out on the gross valuation or on this period's amount?
On a cumulative certificate, retention is a percentage of the gross valuation to date, so the total held grows with the work until any cap is reached. The retention taken this period is the difference between this certificate and the last one. Check your subcontract, because some contracts calculate it differently.
What does a negative net amount mean?
It means the deductions to date, together with what was certified before, exceed the value of the work to date. That can happen after a large contra-charge, a correction to an earlier measurement or an advance recovered faster than the work. Depending on the subcontract, the balance is owed back by the subcontractor or carried to the next certificate.
Are the VAT presets the right rate for my contract?
The presets are the standard rates: 14% in Egypt, 15% in Saudi Arabia and 5% in the UAE. Some construction work is taxed at a different rate, exempt or zero-rated, and the rules change, so confirm the rate that applies to your contract with your tax adviser before you issue a certificate.
Does the calculator save or send my figures?
No. The calculation runs in your browser. The page sends your figures nowhere and stores nothing, so closing the page discards them. Use the copy button to keep a plain-text copy of the certificate, and the reset button to return to the worked example.
Crolle is opening early access to a small group of contractors and partners. To see it on your own projects, write to info@crolle.ai.