- Ontario's Construction Act (formerly the Construction Lien Act) gives lien rights to anyone who supplies services or materials to an "improvement" to real property and isn't paid for it.
- Each category holds a separate, independent lien right.
- Generally excluded, or at least complicated, are: - Suppliers whose materials were never actually delivered to, or used on, the project - Parties whose work wasn't connected to an…
If you supplied labour, materials, or professional services to a construction project in Ontario and haven't been paid, you may be entitled to register a construction lien against the property. But not everyone who touches a job site qualifies, and the rules depend on your role in the contract chain rather than the size of your invoice.
This guide walks through exactly who Ontario's Construction Act protects, who tends to fall outside its reach, and the deadlines that apply once you decide to register a lien.
The Short Answer: Lien Rights Follow the Work, Not the Job Title
Ontario's Construction Act (formerly the Construction Lien Act) gives lien rights to anyone who supplies services or materials to an "improvement" to real property and isn't paid for it. That's a broad, function-based test — it looks at what you actually contributed to the project, not whether you're formally called a contractor, subcontractor, or supplier.
This means lien rights reach well beyond the general contractor. Multiple parties working on the same project, at different levels of the contract chain, can each hold their own independent lien right against the same property.
Who Typically Qualifies
| Role | Typical lien right |
|---|---|
| General contractor | Can lien for unpaid amounts owed directly by the owner |
| Subcontractor | Can lien even without a direct contract with the owner |
| Individual worker or tradesperson | Can lien for unpaid wages for work performed on the project |
| Material supplier | Can lien for materials supplied for the project, subject to the specifics of delivery and use |
| Design professionals (architects, engineers) | Can lien for unpaid professional services connected to the improvement |
Each category holds a separate, independent lien right. A subcontractor's lien doesn't depend on whether the general contractor above them has also registered one, and an unpaid worker doesn't need a supplier's cooperation to protect their own claim.
Who Generally Falls Outside Lien Protection
Not every person or business connected to a project has lien rights. Generally excluded, or at least complicated, are:
- Suppliers whose materials were never actually delivered to, or used on, the project
- Parties whose work wasn't connected to an "improvement" to the property in the sense the Construction Act uses
- Purely financial contributors, such as lenders, who aren't themselves supplying services or materials
Whether a specific situation fits inside or outside these categories can turn on fine detail — exactly what was supplied, to whom, and under what arrangement. If your role is unusual, such as an equipment rental supplier or a project consultant, don't assume either way without checking.
The Clock Starts the Moment Your Work on the Project Ends
Qualifying for a lien is only half the picture — timing matters just as much. Ontario's lien deadlines are short and strict. You generally have 60 days to preserve, or register, your lien, counted from specific trigger dates tied to when your work or supply on the project effectively ended. You then have a further 90 days after the last day you could have preserved the lien to perfect it, which means starting the court action that keeps the claim alive.
Miss either deadline and the lien remedy generally ends, and generally does so permanently. You may still be able to pursue the underlying debt through an ordinary civil claim, subject to Ontario's general limitation period, but you lose the lien's key advantage: a secured claim registered directly against the property. These figures are current as of mid-2026 — always verify them before relying on a specific date for your project.
What to Do If You're Not Sure You Qualify
Because lien rights are broad but the deadlines are unforgiving, the safest approach when you're owed money on a construction project is to get advice early, not after the 60-day window is closing. A lawyer can confirm which category you fall into, calculate your actual deadline, and register the lien correctly so a technical error doesn't undo an otherwise valid claim.
Frequently asked questions
Do I need a written contract to have lien rights?
Not necessarily. Lien rights generally follow from actually supplying services or materials to an improvement, whether the arrangement was a formal written contract, a purchase order, or a verbal agreement. That said, a written contract makes it far easier to prove what you're owed and when your work ended.
Can I still file a lien if I only did a small part of a larger project?
Yes. Lien rights aren't limited to the general contractor or to large-dollar claims. A subcontractor, individual tradesperson, or small supplier can register a lien for their own unpaid portion of the work, independent of what anyone else on the project is owed.
Does it matter if I was paid by the general contractor instead of the property owner?
No — one of the more useful features of Ontario's lien system is that subcontractors and suppliers can generally lien the owner's property even though their contract was with the general contractor, not the owner directly.
What if someone disputes that I'm entitled to lien at all?
That's a factual and legal question the lien registration itself doesn't resolve. Registering preserves your claim, but if the other side disputes your entitlement, you'll need to be ready to establish your role and your unpaid amount through the underlying court process.
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