Ontario prompt payment: 28 days, 7 days, and a new invoice rule

Ontario's prompt payment rules are not a code of conduct. They are deadlines with named consequences, and since 1 January 2026 one of them has moved in the contractor's favour.

The structure of Part I.1 of the Construction Act is a chain. An event starts a clock at the top, and the clock cascades down. Understanding it means understanding what starts it — because until a proper invoice has been given, nothing at all is running. Alberta runs an almost identical chain under its own Act, with one difference that changes everything: Alberta prompt payment: 28 days, 7 days, and a proper invoice.

The chain, in days

That is the whole system. Every number in it is a hard date, and two of them void things: a determination made late "is of no force or effect" (s. 13.13(5)), and a contract clause that conditions invoicing on approval "is of no force or effect" (s. 6.3(2)).

What a proper invoice must contain

Section 6.1(1) defines it as a written bill or other request for payment for services or materials in respect of an improvement under a contract, containing:

"1. The contractor's name and address. 2. The date of the invoice and the period, milestone or other contractual payment entitlement to which the invoice relates. 3. Information identifying the contract or other authorization under which the services or materials were supplied, such as a contract number, contract line item number or purchase order number. 4. A description, including quantity where appropriate, of the services or materials that were supplied. 5. The amount payable for the services or materials that were supplied, and the payment terms. 6. The name, title, mailing address and telephone number of the person to whom payment is to be sent or, if payment is to be sent to an office or department, its name, mailing address and telephone number. 6.1 Any other information that is necessary for the proper functioning of the owner's accounts payable system that the owner reasonably requests. 7. Any other information that may be prescribed."

Item 4 is the one worth pausing on: a description, including quantity where appropriate. A single lump sum with no breakdown is not obviously a description including quantity, and an owner looking for a reason to hold an invoice will find it there.

Item 6.1 was added by the 2024 amendments and is a double-edged provision. It legitimizes an owner asking for a PO number or a cost code — but only what is "necessary for the proper functioning of the owner's accounts payable system" and only where "reasonably request[ed]".

The 2026 change: deficiency now has a deadline

Before 1 January 2026, an invoice that fell short of section 6.1(1) simply was not a proper invoice, and the 28-day clock never started. The owner had no duty to say so. Contractors discovered the problem when the payment did not arrive.

Section 6.1(2) reverses the default:

"An invoice that does not meet the requirements referred to in the definition of 'proper invoice' in subsection (1) is deemed to be a proper invoice for the purposes of this Part unless, no later than seven days after receiving the invoice, the owner notifies the contractor in writing of the deficiency and of what is required to address it."

Two things follow.

Silence now costs the owner. Seven days of no response and the invoice is proper, whatever is missing from it. The 28 days are running.

The notice must be specific. Not "your invoice is deficient" — it must state "the deficiency and … what is required to address it."

The same deeming applies to revised invoices: under s. 6.3(5) a contractor may revise a proper invoice if the owner agrees in advance and the invoice date is not changed, and s. 6.3(6) applies subsection 6.1(2) to a revised invoice with necessary modifications.

Nobody can make you wait for a certifier

Section 6.3(2):

"A provision in a contract that makes the giving of a proper invoice conditional on the prior certification of a payment certifier or on the owner's prior approval is of no force or effect."

This closed the most common way of defeating prompt payment: a contract term saying the contractor may only invoice once the consultant has certified the work. Certification after the invoice remains fine (s. 6.3(3)), and there is a carve-out for testing and commissioning provisions (s. 6.3(4)).

Practically: you invoice on your schedule. If the contract says otherwise, that part of the contract does not exist.

Non-payment down the chain, and the undertaking that costs money

The rule that separates Ontario from most payment legislation is section 6.5(4). If the owner does not pay, the contractor still has to pay its subcontractors — no later than 35 days after giving the proper invoice to the owner.

The only escape is the notice under s. 6.5(5), and it is not a form letter. It must state that the amount is not being paid "due to non-payment by the owner", specify the amount, and provide:

"an undertaking to refer the matter to adjudication under Part II.1 no later than 21 days after giving the notice to the subcontractor"

A copy of any notice of non-payment the owner gave under s. 6.4(2) must be attached.

Read that as what it is: "pay-when-paid" now costs you an adjudication. A contractor who wants to pass the owner's non-payment down the chain has to commit, in writing, to fighting the owner about it within three weeks. Which is exactly what the provision was designed to force.

Where the contractor disputes the subcontractor's entitlement rather than blaming the owner, s. 6.5(6) allows a notice of non-payment "specifying the amount that is not being paid and detailing all of the reasons for non-payment" — no undertaking required, but the reasons have to be complete.

Adjudication: 30 days, and it binds

Part II.1 gives a party to a contract or subcontract the right to refer a dispute to an adjudicator, on a timetable that is fast by any standard.

• When it can be started (s. 13.5(3), (3.1)): an adjudication in respect of a contract may not be commenced if the notice of adjudication is given more than 90 days after the contract is completed, abandoned or terminated, unless the parties agree otherwise — a separate and longer window than the 60-day lien deadline running on the same Act: construction lien deadlines: Ontario and Alberta 60 days, BC 45. For a subcontract the 90 days run from the earliest of that date, the date the subcontract is certified complete under s. 33, or the date the subcontractor last supplied services or materials.
• How long it takes (s. 13.13): the adjudicator must determine the matter "no later than 30 days after receiving the documents required by section 13.11", extendable by up to 14 days with written consent, or by written agreement for a specified period. A late determination "is of no force or effect" (13.13(5)), and reasons must be in writing (13.13(6)).
• What happens next (s. 13.19): the losing party must pay "no later than 15 days after the determination has been communicated to the parties". Interest runs at the prejudgment interest rate under s. 127(2) of the Courts of Justice Act, or the contract rate if higher.
• And the lever (s. 13.19(5)): if the amount is not paid when due, the contractor or subcontractor may suspend further work until paid the determined amount, the accrued interest, and "any reasonable costs incurred … as a result of the suspension of work."

Ninety days is the number to write down. Adjudication is a live-project remedy; once a job has been finished, abandoned or terminated for more than three months, the door closes and you are left with litigation.

Interest, in both places

Section 6.9 applies interest to any amount not paid when due under Part I.1, at the prejudgment interest rate determined under s. 127(2) of the Courts of Justice Act — or, where the contract specifies a different rate, "the greater of the prejudgment interest rate and the interest rate specified in the contract".

A contract that specifies a lower rate does not reduce your entitlement. It is the greater of the two.

What this means for your invoicing

The whole chain hangs on one document. Three habits are enough:

1. Make every invoice a proper invoice on its face — the seven items of s. 6.1(1), with positions carrying descriptions and quantities. The deeming rule in s. 6.1(2) is a safety net, not a plan.
2. Record the date you gave the invoice and the date the owner received it. Every deadline in Part I.1 is counted from receipt, and a fight about lateness is a fight about that date.
3. Diarize three dates per invoice: day 7 (owner's deficiency window closes), day 28 (payment due), day 35 (you must pay your subs regardless).

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Current as of August 29, 2026. This article describes Part I.1 and Part II.1 of Ontario's Construction Act and is not legal advice. It applies to Ontario only; British Columbia, Alberta, Saskatchewan and the other provinces have their own regimes or none. It does not cover the prescribed forms for notices of non-payment, the alternative financing and procurement modifications in s. 1.1, holdback (covered in a separate article), lien deadlines, or judicial review of an adjudicator's determination. The Act is amended frequently — several provisions quoted here came into force on 1 January 2026 — and the version consulted was the consolidation published on Ontario's e-Laws on the date shown.

What Zirko does: it produces documents with individual positions carrying description, quantity, unit and unit price, records payment terms on the document, and keeps interim and final documents on one job. Zirko does not check an invoice against section 6.1(1), does not track the 7, 28 and 35 day deadlines for you, does not produce prescribed notices of non-payment and gives no legal advice. Issued documents are immutable; a correction is a separate document, so a disputed billing history stays readable.