Proper Invoice Under Section 6.1: The Checklist Your Controller Needs

Under the Ontario Construction Act, a proper invoice is what starts the payment clock. Not an email. Not a phone call. Not a PDF that says “Invoice” at the top. A proper invoice, as defined in Section 6.1, triggers the owner's obligation to pay within 28 days. If your invoice doesn't meet every requirement, the clock never starts. Your money sits.

This is the single most common reason payment stalls on ICI projects. The contractor thinks they invoiced. The owner's accounts payable flags the document as incomplete. Nobody picks up the phone. Weeks pass.

Here is what Section 6.1 actually requires, line by line. Share this with your controller.

The Section 6.1 Checklist

Every proper invoice must include all of the following. Miss one, and the owner has grounds to issue a deficiency notice.

1. Contractor's name and address. Full legal name as it appears on the contract. Not a trade name unless that's what the contract uses.
2. Date of the invoice and the period covered. The invoice date is the date you issue it. The period is the date range during which the services or materials were supplied. Both are required.
3. Contract reference. The information identifying the authority under which services or materials were supplied. This typically means your contract number or purchase order number.
4. Description of services or materials, including quantity. “Labour and materials” is not enough. The Act says “including quantity where appropriate.” If you installed 400 linear metres of ductwork, say so.
5. Amount payable and payment terms. The dollar amount owing, plus the payment terms from your contract. If your contract says net 28 days, state it.
6. Project site name and address. The physical location where the work was performed. On multi-site contracts, be specific.
7. Any other information the contract requires. Read your contract. Many ICI contracts require WBS codes, cost codes, or schedule of values references. If the contract says it, the invoice needs it.
8. Any information necessary for the proper functioning of the owner's accounts payable system (new in 2026). This is the newest addition. The owner can reasonably request information their AP system needs to process the invoice. Think PO numbers, GL codes, or digital format requirements. The key word is “reasonably.” An owner cannot use this to create impossible requirements.

The 7 Day Deeming Rule

This is the provision that changes everything for 2026.

Read that again. Seven calendar days. Not business days. If the invoice lands on a Friday and nobody reviews it until the following Monday, you've already burned three of your seven days.

The notice must be in writing and must identify the specific deficiency. A vague “this invoice is incomplete” email does not satisfy the requirement. The owner must say exactly what is missing.

What This Means for Contractors

Your invoices need to be bulletproof. Every field, every time. One missing element gives the owner a legitimate reason to issue a deficiency notice, which resets the clock once you resubmit.

Build a template that maps to all eight Section 6.1 requirements. Before you send an invoice, run it against the checklist above. Better yet, build the checklist into your billing workflow so nobody can skip a field.

Pay attention to requirement eight. Ask the owner early in the project what their AP system needs. Get it in writing. If they add new requirements mid-project, that's a conversation worth having before it becomes a dispute.

Common Mistakes That Trigger Deficiency Notices

• Using a trade name instead of the legal entity name on the contract
• Omitting the service period (just putting the invoice date)
• Vague descriptions like “progress billing” with no quantities
• Missing the project site address on multi-location contracts
• Forgetting contract-specific requirements like WBS codes

What This Means for Owners

You have a hard seven day deadline to review every incoming invoice. Not seven days from when your payment certifier gets around to it. Seven days from when the invoice arrives at whatever address or portal the contract specifies.

If the invoice lands in the wrong inbox, the clock still runs. If your payment certifier is on vacation, the clock still runs. If your AP coordinator doesn't realize the invoice is missing a cost code, and nobody sends written notice within seven days, the invoice is deemed proper. You now owe payment within 28 days of receipt.

The deeming rule also means your deficiency notice must be specific. You cannot send a blanket rejection. You must identify which of the eight requirements is not met and explain what is missing.

Where Software Fits

This is exactly the kind of validation that should not depend on a human remembering eight requirements while processing 30 invoices on a Friday afternoon.

A proper system validates each invoice field against Section 6.1 at the point of submission. Missing the project site address? The invoice doesn't go through. No contract reference? Flagged immediately. The contractor fixes it before it even reaches the owner, which means no deficiency notice, no reset clock, no delayed payment.

On the owner side, automated intake with a 7 day countdown timer eliminates the risk of a deemed proper invoice slipping through. Every invoice gets a timestamp on receipt, a review assignment, and a deadline alert.

The Section 6.1 proper invoice is a straightforward checklist. The hard part is making sure it gets followed on every invoice, on every project, every single time. That's what systems are for.