Proper Invoice Under Ontario’s Construction Act: Sample, Template, and 6-Field Checklist (2026)

Ontario’s Construction Act sets a 28-day payment clock. But that clock only starts when you send a proper invoice. Send an invoice that’s missing even one of the required fields and the owner can issue a deficiency notice, the clock never starts, and you’re back to square one.

Most trade contractors in Ontario don’t know this rule exists. They use a Word template or a QuickBooks default, send it off, and then wonder why payment is still outstanding six weeks later. The reason is usually a missing field: no period of work, no contract reference, or no named person to send payment to.

This article breaks down exactly what section 6.1 of the Ontario Construction Act requires, shows a compliant sample invoice, and gives you a six-field pre-send checklist. For broader context on how the full 28-day system works, including the payment chain, dispute windows, and what to do if a customer does not pay, see the Ontario Construction Act prompt payment guide or the 2026 Construction Act amendments guide.

Why “proper” matters: the 28-day clock won’t start without it

The prompt-payment regime under the Construction Act is powerful, but it is conditional. Section 6.4 says the owner must pay within 28 days of receiving a proper invoice. Not just any invoice: a properinvoice. If your invoice does not meet the definition in section 6.1, the 28-day obligation never attaches.

Before January 1, 2026, an owner had 14 days to issue a deficiency notice pointing out missing fields. That window was cut to 7 days by the 2026 amendments (confirmed in O. Reg. 306/18). So the feedback loop is faster now. But missing a field still resets the clock to zero once a deficiency notice arrives.

Note the distinction between two separate notices:

• Deficiency notice (7 days): issued when the invoice is missing required fields. The clock never started in the first place.
• Notice of Non-Payment (14 days): issued when the invoice is a proper invoice but the owner disputes the amount. The clock did start; the owner is disputing the sum.

A deficiency notice is far more damaging to your cash flow because it means you have to reissue and start over. Get the fields right the first time.

The 6 mandatory fields under section 6.1

Section 6.1 of the Construction Act lists the information a proper invoice must contain. Here is each item, in the order the Act lists it, translated from statutory language into plain contractor terms. (The Act also allows for any other information prescribed by regulation, and your contract can add requirements on top.)

1. Your name and address

The contractor’s name and address. Use your legal or registered business name and a full mailing address, not just a phone number or a logo.

Example: “Kowalski Electric Inc., 12 Workshop Lane, Toronto ON M4M 1A1”

2. Invoice date and period of work

The date of the invoice andthe period during which the services or materials were supplied. The period of work is the single most commonly missing item. Use a specific date range, not “upon completion.” Note that the 28-day payment clock runs from the day your customer receives the invoice, not from the date printed on it, so keep proof of when you delivered it.

The period of work also matters for lien purposes: your lien rights depend on the last day you supplied services, and the invoice is the primary record.

Example: “Invoice date: May 8, 2026. Work performed: April 7 to 18, 2026”

3. Contract reference

Information identifying the authority, in the contract or otherwise, under which the work was done. In practice, a job address combined with a contract date is the safest approach. A purchase order number also works if one was issued.

Example: “Per contract dated April 3, 2026, for panel upgrade at 412 Lakeshore Rd., Burlington, ON”

4. Description and quantities

A description of the services or materials supplied, including quantities where appropriate. Vague descriptions like “labour and materials” do not do the job. A line-item breakdown is the clearest format and the hardest to dispute.

Example: “Labour: 24 hrs @ $120/hr. Materials: 200A panel, breakers and wire (schedule attached).”

5. Amount payable and payment terms

The amount payable for the services or materials supplied, and the payment terms. Show how you got to the number (hours times rate, materials, a reference to a schedule of values) and state when payment is due.

Example: “Labour $2,880. Materials $1,320. Subtotal $4,200. HST $546. Total $4,746. Payment due within 28 days of receipt.”

6. Payment remittance contact

The name, title, telephone number and mailing address of the person to whom payment is to be sent. Putting your business address at the top of the letterhead isn’t enough on its own. The remittance contact is a separate, explicitly required item.

Example: “Remit payment to: Jamie Kowalski, Owner, Kowalski Electric Inc., 12 Workshop Lane, Toronto ON M4M 1A1, (416) 555-0142.”

Many contractors also add a typed “Authorized by:” line for clarity. That’s good practice, but it doesn’t replace the remittance contact.

Not a Construction Act field, but still required: your GST/HST number

Section 6.1 does not mention sales tax, but the CRA does. For your customer to claim an input tax credit on an invoice of $100 or more, it must show your GST/HST registration number and either the amount of tax charged or a statement that the price includes it. Showing the tax on its own line is the clearest way to do that.

Example:“HST 13% (BN 123456789 RT0001): $546.00”

The “seventh field”: what owners can reasonably demand

Section 6.1(6.1), added by the 2026 amendments, allows owners to require additional information that is necessary for the proper functioning of their accounts payable system, as long as the request is reasonable. This means an owner can ask for a purchase order number, a cost-code breakdown, or a specific invoice format, provided they notify you in advance.

Two things owners cannot require: they cannot make a proper invoice conditional on the owner’s approval, and they cannot make it conditional on payment certification. Those requirements would let owners delay the clock indefinitely, which is exactly what the Act was designed to prevent.

Practical advice: ask at contract signing whether the owner has an AP system with specific requirements. Get the list in writing. Add those fields to your template for that project so every invoice is compliant from day one.

Sample compliant invoice

The table below shows what a compliant proper invoice looks like for a typical trades contractor in Ontario. All six mandatory fields are present.

Want to see it as a finished document? Download this sample invoice as a PDF. It is the invoice Markup produces for this job, with fictional details. It also shows a 10% holdback line, so the amount due is $4,326.00 rather than the $4,746.00 total.

The remittance contact (name, title, mailing address, telephone) IS one of the six mandatory section 6.1 fields, even though it’s often overlooked. Including it removes any excuse for a misrouted payment.

The 7-day deficiency notice rule

As of January 1, 2026, an owner has exactly 7 days from receiving your invoice to issue a deficiency notice if they believe it is not a proper invoice. If they miss that window, the invoice is deemed to be a proper invoice regardless of any missing fields, and the 28-day payment clock runs from the date they received it.

Before 2026 there was no deadline at all. An owner could say weeks later that an invoice was missing something, and the 28-day clock had never started. The new rule helps contractors: an owner who wants to reject an invoice as deficient has to say so in writing within 7 days, and say what is needed to fix it.

What the deficiency notice must contain (as tightened by the 2026 amendments):

• The specific field or fields that are deficient (a generic “invoice is incomplete” will not satisfy the requirement).
• What the contractor must do to address the deficiency.
• Any amounts the owner intends to withhold pending correction.

A vague or over-broad deficiency notice can itself be invalid. If you receive one, read it carefully. If it does not identify a specific missing field, consider responding in writing that the notice does not satisfy the Act and that the 28-day clock is running. Keep records of every send date and every response.

This is separate from the Notice of Non-Payment process. A Notice of Non-Payment (Form 1.1) is used when the invoice is a proper invoice but the owner disputes the amount or quality of work. That notice must arrive within 14 days of the proper invoice and must itself be specific about the disputed amount and reason. For more on the adjudication path after a dispute, see our article on ODACC adjudication in Ontario.

Pre-send checklist

Run through this before you send any invoice for construction work in Ontario. It takes 60 seconds and it is the difference between starting the 28-day clock and getting a deficiency notice.

If every row passes, send the invoice and note the date. Your 28-day clock starts on receipt. Set a reminder for day 7 (deficiency notice window closes), day 21 (one week out, send a courteous follow-up), and day 28 (payment due). Also check your lien deadline separately: it runs from the last day you supplied services, not from the invoice date, and missing it means you permanently lose your most powerful collection tool.

This article is for general information only and does not constitute legal advice. For advice specific to your situation, consult a construction lawyer licensed in Ontario.